S for save, S for silent and S for Schaller strap locks!
Belt pins:
Specially turned 4.5 mm wood thread in S-Lock size L for maximum hold.
External thread 4.5 mm, internal 3.2 mm, length 27 mm.
These new revolutionary S-Locks include unique one-piece strap pins made of the hardest steel, locks that fit every leather strap with ergonomic operation and patented locking nuts with triple security architecture.