Schaefer blocks have been manufactured in the United States since 1966 and are known for their legendary strength. Blocks are made from 316 stainless steel and hard coat anodized 6061-T6 aluminum alloy while the sheaves are made of UV protected Delrin. Schaefer offers the widest range of products for building block and tackle systems. Flat, stainless base plate distributes loads to a larger surface area than other designs that place loads on the mounting bolts only. Use on spars and deck to lead sheets, halyards, reefing gear and any control requiring a strong, smooth lead.