Series 40 Ball Bearing Orbit Block - CheekFeatures:Ultra LightweightLow friction 2-stage Orbital ball bearing systemHighest working load in its classLow profile and compactHigh performance cleatingBase suits curved mounting surfaceLow mounting points for maximum strengthLightweightKilogram for kilogram of working load, BB and RT Orbit Blocks™ are the world’s lightest. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimizes the mass of the inactive return race and hub.Weight and bulk are further reduced in the different block configurations. The ball bearing single and becket block has a through-sheave becket arrangement. The result? The lowest weight possible.Multi-sheave blocks have only single intermediate cheeks and an ultra-light and efficient head arrangement. This gives a 30% weight saving advantage over the nearest competitor. Other brands just link together their single blocks. This results in unnecessary double cheeks between each sheave, held together by a heavy steel channel across the top of the block.Highest Working Load In It's ClassThe orbital ball-bearing arrangement gives the largest possible bearing race diameter. This maximizes load performance. The proven Ronstan 2-stage bearing system features high compression grade acetal ball bearings and a secondary full-contact bearing. This gives minimum friction across the full working load range.The floating sheave and bearing system is supported by a fiber-reinforced load frame. The design was computer modeled to be stress optimized.Recommended fasteners - 3 x 4mm (5/32") countersunk head screwsApplications:Mainsheet systems on spinnaker sheet on dinghies to 5m (16ft)Spinnaker sheets on dinghies, sportsboats and small keel boats to 5m (16ft)Halyard, vang and backstay applications on boats to 8m (26ft)Control line applications on larger yachtsMaterials:Ball Bearings - High compression strength carbon black Acetal.Stage 2 Bearing - Glass fibre reinforced, MoS2 impregnated NylonFrame/Cheeks - Toughened, glass fibre reinforced NylonSheave - Carbon fiber reinforced, PTFE impregnated Nylon