Check the listing for details. Ronstan Series 40 All Purpose Block - Double Block - Full Swivel Head. Condition: New. Listed at 50.22 USD. Series 40 All Purpose Block - Double Block - Full Swivel Head All purpose (AP) blocks are a great all around solution. Self-lubricating Acetal polymer sheaves running on polished stainless steel races perform equally well with dynamic loads and high static loads. For durability and a long service life, these blocks are the right choice for sheets, halyards and control line applications for cruising and racing. Head swivels freely. Features: Exceptionally high working loads Low maintenance, long service life Self-lubricating sheave Slotted pin shackle eliminates fouled lines Two way head post Applications: Mainsheet Halyard Vang Spinnaker control lines on off-the-beach catamarans, one design classes and sportsboats up to 8M(26') Materials: U.V. stabilized Acetal sheaves Impact and U.V. resistant, fiber reinforced Nylon cheeks Grade 316 stainless steel bearing race Grade 316 stainless steel load strap and head fitting Specifications: Sheave Ø: 40mm(1-9/16") Max. Rope Ø: 10mm(7/16") Pin Ø: 5mm(3/16") M.W.L.: 600kg(1,320lbs) B. L.: 1,200kg(2,650lbs) Weight: 135g(4.8oz)