Carbo fiddle blocks have black nylon bodies reinforced with long strand glass for exceptional strength and light weight. They feature high-load ball bearings with rounded races for high contact, low friction operation. Shackles on 57 mm blocks can be locked at 90 intervals using the Cam-Lock locking system, or left to swivel freely Cam arm assemblies can be adjusted in a wide range of positions Open design makes for easy maintenance See separate entry for ratchet fiddle blocks