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. 7 series blocks offer medium sized cruising and racing yachts with a stunning combination of strength and performance. Their robust yet lightweight construction produces an exceptionally strong block built to perform well past other plastic designs.