Ronstan Series 50 High Load Block - Single - Universal Head - RF50100HLSeries 50 High Load Block Single Universal Head Ideal for high load applications. Wear resistant sheave material, in lightweight, self lubricating polymer, is suitable for use with rope or wire. Captive Lock universal head can be fixed in either of two planes, or free to swivel as required. Features: Exceptionally high working loads Lightweight Cheek cut outs for easy bearing maintenance Suitable for both rope or wire Captive Lock universal head