Series 31E
Hand fine matt grounded stainless steel case with 42 mm diameter, finely decorated hand winding Unitas pocket watch movement modified to an indirect center second and a deep black contrast dial with handmade hour and minute hands. The new Model 31E is certainly one of the best pilot watches we've ever built.

An extraordinary pilot watch
For our Series 31E we use a fully satinized i.e. by hand fine matt grounded stainless steel case with 42 mm diameter and 11.95 mm height and recase the HS81 manual wound movement in it. This watch is powered by the finely decorated hand winding Unitas pocket watch movement which is modified to an indirect center second and a special feature, which is visible only for the view of the wearer - the seconds zeroing.
To precisely set the time of a wrist watch most movements are equipped with a second stop – when the crown is wound, the second hand doesn’t move. The seconds zeroing is a much rarer design. When the crown is wound, the second hand continues to run until it reaches “60” and then it automatically stops – thus it is possible to use a time signal to set the watch to the second.
Contemporary our model 31E is pressure-resistant up to 10 bar and equipped with sapphire glasses on front and back side. The watch wears a deep black contrast dial and handmade hour and minute hands. Like all the hour indices and the marking triangle, these steel pointers made in Saxony are coated with white luminescent material.
For the love of details
Also this watch was developed and built entirely in Germany - that is, Case, dial, hands, bracelet and clasp are all produced in Germany. The pocket watch movement we use is decorated, modified and regulated in our workshop in 5 positions. For this reason we engrave “Frankfurt” on the watch back.
Made in Germany
Technical details
Movement
- Calibre HS 81
- Base: UNITAS 6497 Lépine. Modified as per a construction by Helmut Sinn
- Indirect center second
- Second stop at 60 when crown is pulled
- 18 jewels
- 18000 vibrations per hour; 2.5 Hz.
- Movement diameter 16 1/2‘‘‘ (36,6 mm)
- Incabloc shock protection
- Glucydur balance
- Nivarox hairspring
- Triovis precision adjustment system
- Movement decorated with Geneva Stripes , blued screw hads, crown wheel and ratchet wheel with solar finish
- Power reserve approx. 40 hours
Functions
- Hours, minutes, indirect center second
- Second stop at 60 when crown is pulled
Case
- Stainless steel hand satinized
- Sapphire crystal glass, domed, anti-reflective on the interior
- Screwed back with sapphire crystal glass
- Crown double sealed
- Waterproof, vacuum resistant and pressure resistant up to 10 bar
Dimensions and Weight
- Case diameter: 42 mm
- Band lug width: 20 mm
- Lug to lug distance: 50.9 mm
- Distance between the spring bars: 46 mm
- Case thickness: 12.35 mm
- Weight without strap: 67 grams
Watch configurator
Straps 20 mm
Leather Strap Arizona

Black Cowhide with alligator embossing.
Available with a pin or folding clasp.

Red-brown Cowhide with alligator embossing.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 190 mm | 185 mm | 191 mm | 186 mm |
ideal wrist circumference in inch | 7.5 in | 7.3 in | 7.5 in | 7.3 in |
max. wrist circumference in mm | 210 mm | 205 mm | 211 mm | 206 mm |
max. wrist circumference in inch | 8.3 in | 8.1 in | 8.3 in | 8.1 in |
min. wrist circumference in mm | 170 mm | 165 mm | 171 mm | 166 mm |
min. wrist circumference in inch | 6.7 in | 6.5 in | 6.7 in | 6.5 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Cordovan

Black cordovan, cushioned.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 189 mm | 184 mm | 190 mm | 185 mm |
ideal wrist circumference in inch | 7.4 in | 7.2 in | 7.5 in | 7.3 in |
max. wrist circumference in mm | 209 mm | 204 mm | 210 mm | 205 mm |
max. wrist circumference in inch | 8.2 in | 8.0 in | 8.3 in | 8.1 in |
min. wrist circumference in mm | 166 mm | 161 mm | 167 mm | 162 mm |
min. wrist circumference in inch | 6.5 in | 6.3 in | 6.6 in | 6.4 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Monza

Dull finished calf leather with white contrast stitching, BR-padded.
Available with a pin or folding clasp.

Dull finished calf leather with orange contrast stitching, BR-padded.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 185 mm | 180 mm | 186 mm | 181 mm |
ideal wrist circumference in inch | 7.3 in | 7.1 in | 7.3 in | 7.1 in |
max. wrist circumference in mm | 205 mm | 200 mm | 206 mm | 201 mm |
max. wrist circumference in inch | 8.1 in | 7.9 in | 8.1 in | 7.9 in |
min. wrist circumference in mm | 167 mm | 162 mm | 168 mm | 163 mm |
min. wrist circumference in inch | 6.6 in | 6.4 in | 6.6 in | 6.4 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Rally

Soft cowhide leather with fine punching.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 185 mm | 180 mm | 186 mm | 181 mm |
ideal wrist circumference in inch | 7.3 in | 7.1 in | 7.3 in | 7.1 in |
max. wrist circumference in mm | 205 mm | 200 mm | 206 mm | 201 mm |
max. wrist circumference in inch | 8.1 in | 7.9 in | 8.1 in | 7.9 in |
min. wrist circumference in mm | 167 mm | 162 mm | 168 mm | 163 mm |
min. wrist circumference in inch | 6.6 in | 6.4 in | 6.6 in | 6.4 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Rotte

High-quality watch strap made of anthracite-colored wild boar leather.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 183 mm | 178 mm | 184 mm | 179 mm |
ideal wrist circumference in inch | 7.2 in | 7.0 in | 7.2 in | 7.0 in |
max. wrist circumference in mm | 203 mm | 198 mm | 204 mm | 199 mm |
max. wrist circumference in inch | 8.0 in | 7.8 in | 8.0 in | 7.8 in |
min. wrist circumference in mm | 160 mm | 155 mm | 161 mm | 156 mm |
min. wrist circumference in inch | 6.3 in | 6.1 in | 6.3 in | 6.1 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Rotte XL

High-quality watch strap made of anthracite-colored wild boar leather in XL length.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 192 mm | 187 mm | 193 mm | 188 mm |
ideal wrist circumference in inch | 7.6 in | 7.4 in | 7.6 in | 7.4 in |
max. wrist circumference in mm | 223 mm | 218 mm | 224 mm | 219 mm |
max. wrist circumference in inch | 8.8 in | 8.6 in | 8.8 in | 8.6 in |
min. wrist circumference in mm | 161 mm | 156 mm | 162 mm | 157 mm |
min. wrist circumference in inch | 6.3 in | 6.1 in | 6.4 in | 6.2 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Chronissimo (normal length)

Black cowhide, integrated in the case.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 213 mm | 208 mm | 214 mm | 209 mm |
ideal wrist circumference in inch | 8.4 in | 8.2 in | 8.4 in | 8.2 in |
max. wrist circumference in mm | 232 mm | 227 mm | 233 mm | 228 mm |
max. wrist circumference in inch | 9.1 in | 8.9 in | 9.1 in | 8.9 in |
min. wrist circumference in mm | 192 mm | 187 mm | 193 mm | 188 mm |
min. wrist circumference in inch | 7.6 in | 7.4 in | 7.6 in | 7.4 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Chronissimo (short length)

Black cowhide, integrated in the case.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 197 mm | 192 mm | 198 mm | 193 mm |
ideal wrist circumference in inch | 7.8 in | 7.6 in | 7.8 in | 7.6 in |
max. wrist circumference in mm | 216 mm | 211 mm | 217 mm | 212 mm |
max. wrist circumference in inch | 8.5 in | 8.3 in | 8.5 in | 8.3 in |
min. wrist circumference in mm | 174 mm | 169 mm | 175 mm | 170 mm |
min. wrist circumference in inch | 6.9 in | 6.7 in | 6.9 in | 6.7 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Antique

Pull up leather with laquered edging and colored stitch.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 191 mm | 186 mm | 192 mm | 187 mm |
ideal wrist circumference in inch | 7.5 in | 7.3 in | 7.6 in | 7.4 in |
max. wrist circumference in mm | 210 mm | 205 mm | 211 mm | 206 mm |
max. wrist circumference in inch | 8.3 in | 8.1 in | 8.3 in | 8.1 in |
min. wrist circumference in mm | 170 mm | 165 mm | 171 mm | 166 mm |
min. wrist circumference in inch | 6.7 in | 6.5 in | 6.7 in | 6.5 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Leather Strap Vintage Brown

Saddle leather with light contrast stitching, at tip of strap and at lug ends.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 190 mm | 185 mm | 191 mm | 186 mm |
ideal wrist circumference in inch | 7.5 in | 7.3 in | 7.5 in | 7.3 in |
max. wrist circumference in mm | 210 mm | 205 mm | 211 mm | 206 mm |
max. wrist circumference in inch | 8.3 in | 8.1 in | 8.3 in | 8.1 in |
min. wrist circumference in mm | 178 mm | 173 mm | 179 mm | 174 mm |
min. wrist circumference in inch | 7.0 in | 6.8 in | 7.0 in | 6.9 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Rubber Strap Glatt

Black rubber strap, smooth surface,
incl. a laser engraved folding-clasp satinated or bead-blasted
Textile Strap Safety Belt

Highend textile strap with a soft inlay.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 187.5 mm | 182.5 mm | 188.5 mm | 183.5 mm |
ideal wrist circumference in inch | 7.4 in | 7.2 in | 7.4 in | 7.2 in |
max. wrist circumference in mm | 208 mm | 203 mm | 209 mm | 204 mm |
max. wrist circumference in inch | 8.2 in | 8.0 in | 8.2 in | 8.0 in |
min. wrist circumference in mm | 167 mm | 162 mm | 168 mm | 163 mm |
min. wrist circumference in inch | 6.6 in | 6.4 in | 6.6 in | 6.4 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Silicone Strap S60

Black silicon strap integrated in the case with white seam.
Available with a pin or folding clasp.
Cases 20 mm | Type 40 | Type 60 | Type 31 | Type 155 |
---|---|---|---|---|
ideal wrist circumference in mm | 191 mm | 186 mm | 192 mm | 187 mm |
ideal wrist circumference in inch | 7.5 in | 7.3 in | 7.6 in | 7.4 in |
max. wrist circumference in mm | 213 mm | 208 mm | 214 mm | 209 mm |
max. wrist circumference in inch | 8.4 in | 8.2 in | 8.4 in | 8.2 in |
min. wrist circumference in mm | 172 mm | 167 mm | 173 mm | 168 mm |
min. wrist circumference in inch | 6.8 in | 6.6 in | 6.8 in | 6.6 in |
Wrist circumference specifications are approx. values and depend on the individual wearing habits.
Solid Strap Typ 3.1

Solid stainless steel sports strap
Solid Strap Typ 3.1-V

Solid stainless steel sports strap with a quickly adjustable folding clasp
Solid Strap Typ H

Stainless steel strap Typ H polished/satinated
Solid Strap Typ H matte

Stainless steel strap Typ H bead blasted