60 mm Ball Bearing Block - Single, Swivel Backstay The locking arms are spring-loaded

The locking arms are spring-loaded to prevent accidential locking

The BBB40 Triple Becket Swivel Block is equipped with three 40 mm sheaves

Safe working Load: 325 kg

That means

Hole distance is c-c 100 mm

60 mm Ball Bearing Block - Single, Swivel Backstay The locking arms are spring-loadedThe BBB60 Single Swivel Block is a 60 mm ball bearing block with a swiveling shaft. A plastic washer, acting as a swivel lock, is placed between the block body and the shackle to lock the shackle at either 0 or 90. The block features Delrin ball bearings for smooth rotation and glass fiber reinforced cheeks for strength. Ideal for use with mainsail, genoa, and spinnaker sheets, or control lines, in both static and dynamic load applications. Safe