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. Halyard/Control Blocks are excellent for fixed position halyard, sheet or control line fairleads. Block swivels 360 degrees, tilts in all directions and is supported by a heavy gauge stainless steel sprint to prevent deck contact. Large diameter base helps distribute loads to a larger surface area than other smaller designs.