Ronstan Series 75 Core Block - Single - Aluminum Rope/Wire Sheave [RF74100AW]Series 75 Core Block Single Aluminum Rope Wire Sheave Core Blocks are a true all round solution. A tuned 2 stage bearing system provides excellent performance across the full working load range with an integrated thrust bearing feature and the resilience to handle high dynamic or static loads. Acetal sheave, alloy cheeks and stainless fixings complete the durable package. For reliability and a long service life, these blocks are the right choice for