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