Sinn
Instrument Chronographs 356.0721— lug 20mm

The Sinn 356.0721 features a 20 mm lug width, a classic standard for European aviator chronographs. This measurement accommodates both slim tapered straps and robust NATO solutions whilst maintaining balanced proportions on the 38.50 mm case diameter.

Natural alligator with vegetable tanning or shell cordovan accentuates the instrumental identity without aesthetic conflict. For military contexts or high-friction environments, a polyamide NATO woven strap offers minimal maintenance and superior grip. Vegetable-tanned calf in cognac or tobacco brown introduces controlled warmth whilst preserving sobriety.

Use a Spring Bar Remover tool, inserting the flat tip into the lateral slots housing the lug pins. Apply gradual downward pressure to release the spring-loaded pin, then extract the old strap. Reinsert the new one by aligning the pins to the lugs and press until the click locks into place.

Entirely compatible. An aftermarket strap with 20 mm lug width fits perfectly without adapters. Verify the lug slot is manufactured for this precise width using a calliper, and confirm the pin diameter is standard 1.5 mm for secure insertion into the case holes.

A quality leather strap (alligator, shell cordovan or vegetable-tanned calf) lasts 3–5 years in moderate daily use, with visible patina development within 6–12 months. Protect the strap from prolonged rainfall and intense perspiration by applying a conservation cream every 3 months. Replacement recommended every 4–5 years to prevent sudden failure.