Ronstan Series 55 Ball Bearing Orbit Block - Single - Becket - Swivel Head. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimises 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 30percent 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. Specifications for Ronstan Series 55 Ball Bearing Orbit Block: Manufacturer: Ronstan Color: Black Features of Ronstan Series 55 Ball Bearing Orbit Block Ultra Lightweight Low friction 2-stage Orbital ball bearing system Highest working load in its class Low profile and compact High performance cleating Swivel shackle head for unlimited block rotation Stainless steel shackle head for ultimate durability and compatibility with harsh fixing points Ultra low profile integrated becket Applications: Mainsheet systems on dinghies sportsboats and small keelboats to 9M(30') Spinnaker sheets on dinghies sportsboats and small keel boats to 9M(30') Halyard Vang and Backstay application on boats to 8M(26') Control line applications on larger yachts Ideal use for mainsheet systems and spinnaker sheets on dinghies sportsboats and small keel boats to 9M(30') Also ideal with halyard vang and backstay applications on boats to 8M(26') Spinnaker sheets on sportsboats and small keel boats (lateral lead blocks) Control line applications on larger yachts Materials: Ball bearings - High compression strength carbon black Acetal Stage 2 bearing - Carbon fiber reinforced PTFE impregnated Nylon Frame/Cheeks - Toughened glass fiber reinforced Nylon Rope Link: UV stabilized multi-strand impregmented SK75 Dyneema Sheave: Carbon fiber reinforced PTFE impregnated Nylon Head fitting: Grade 316 stainless steel. : Sheave : 55mm(2-5/32") Max. Rope : 10mm(3/8") M.W.L.: 500kg(1100lbs) B. L.: 1000kg(2200lbs) Weight: 88g(3.1oz) Package Contents: Ronstan Series 55 Ball Bearing Orbit Block Ronstan RF55110: Series 55 Ball Bearing Orbit Block - Single - Becket - Swivel Head