Gennaker Pole Launch 'back to back' Blocks. You can use any manufacturer for these - but the Harken Micro 22mm are super reliable. Sheave: 22mm (7/8") Length: 71mm (2-3/4") Weight: 35g (1.25oz) Maximum Line: 6mm (1/4") Maximum Working Load: 91kg (200lb) Breaking Load: 544kg (1200lb) Read more