The 15.25 mm pin lock, is needed to be able to fold the Leshiy 2 when an aluminum handguard is installed (Muzzle Brake, Shelest, Shopot, Tishina 150, and Tishina 200 kits)

The 16 mm pin lock, instead, is needed to be able to fold the Leshiy 2 when a carbon fiber handguard is installed (Shorokh kit)