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. Unique curved stainless base plate fits up to 2 inch diameter spar section for easy mounting. Excellent for control line leads on dinghys and small daysailors.