Like the 5 Series blocks, but with Schaefer's ball-bearing sheave. Curved ball races allow Schaefer ball-bearing blocks to take higher loads than other similarly sized blocks.
5 Series blocks offer small to medium-sized cruising and racing yachts an extremely high strength/weight ratio resulting in a highly refined and reliable block. The versatile universal head design has a three-way built-in locking feature and accepts Schaefer "universal" adapters for custom mounting.
5 series blocks are offered with Aluminum cheeks and plain bearing sheaves (504 series), Stainless Steel cheeks and plain bearing sheaves (505 series), and Aluminum cheeks and Delrin (tm) ball bearing sheaves (506 series).
