Ronstan's Series 40 All Purpose 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. The Captive Lock™ universal head can be fixed at 0° or 90°, or left free to swivel and the removable becket pin allows lines to be spliced prior to fitting.