Harken 40mm Double Sheave Fishing Block [2184]40mm Double Sheave Fishing Block Low friction Carbo Air blocks are lightweight, strong, and reliable. These compact blocks have very high working loads and smooth operation to simplify the positioning and retrieval of teaser lines. Specifications: Sheave (mm): 40 mm Sheave (in): 1 9 16 in Maximum line (mm): 10 mm Maximum line (in): 3 8 in Maximum working load (kg): 220 kg Maximum working load (lb): 485 lbs