Add quick-release function to Synchro blocks. Cruisers love Lewmar Synchro blocks for their strength and ability to adapt to different applications; adding a snap shackle makes them all the more versatile. These snap shackles are designed to replace the existing standard shackle on Synchro blocks and are also compatible with the Lewmar HTX and Control Block lines. Each pin is engineered to mate perfectly with the blocks shackle post to maximize contact and prevent wear. Use the selection table below to identify the correct snap shackle for your blocks. Make your existing blocks even more versatile by swapping out the standard shackle for a Lewmar Synchro snap shackle. Key Features Adds quick-release capabilities to Synchro, HTX and Control blocks Pin diameters are engineered for maximum contact with blocks shackle post to reduce wear 316 stainless steel construction for excellent strength and superior corrosion resistance Ring pull releases shackle to move or stow Available in several sizes to mate with different Lewmar series blocks May be compatible with other blocks; use dimensions in the table below to confirm sizing Selection GuideModelFitsWorking Load LimitBreaking LoadPin DiameterMax Shackle Post DiaFork Depth (Pin to Top of Shackle Post)Interior Shackle OpeningFits 50mm50 Synchro / 30 & 40 Control Single / Double990 lbs. (450 Kg)1980 lbs.(900 Kg)1∕8" (4mm)3/8" (9mm)3/16" (4.5mm)1/2" (12mm)Fits 60mm60 Synchro / 50 HTX / 30 Control Triple1760 lbs. (800 Kg)3520 lbs. (1600 Kg)3∕16" (5mm)1/2" (12mm)1/4" (6mm)9/16" (14mm)Fits 72mm72 Synchro / 60 HTX / 40 Control Triple2420 lbs. (1100 Kg)4840 lbs. (2200 Kg)1∕4" (6mm)1/2" (13mm)1/4" 6.5mm)11/16" (18mm)Fits 90mm90 Synchro / 72 HTX4400 lbs. (2000 Kg)8800 lbs. (4000 Kg)3∕8" (9.5mm)11/16" (17.5 mm)5/16" (7.5mm)7/8" (22mm)