Schaefer's Blocks rely on a variety of sheaves designs and scorings. Schaefer
sheaves are design to be compatible with Schaefer products. There is
a risk of incompatibility or failure when using Schaefer sheaves in blocks
manufactued by anyone other than Schaefer Marine. Schaefer Delrin™ Sheaves
are injected molded with UV inhibitors and monitored molding cycles lending
to a strong, UV resistant
product. These sheaves offer durable, lasting service for all line applications.