This all-purpose blockis a great all around solution. A self-lubricating Acetal polymer sheaveensures low friction and is extremely durable.This blockis the right choice for sheets, halyards and control line applications for cruising and racing. The Captive Lock universal head can be fixed in either of two planes, or free to swivel as required. High working load Low maintenance, long service life Sheave Size: 54 + 34 mm Line Diameter: 10 mm Lockable swiveling head post Slotted pin shackle eliminates fouled lines Grade 316 stainless steel load strap Impact and UV resistant, fiber reinforced Nylon cheeks Self-lubricating Acetal polymer sheave ensures low friction and extreme durability