CR-D Chain Swivel (TYPE SW4) The SW4 series represents GN Rope Fittings’ specialized engineering for versatile mooring and chain rotation. These CR-D (Chain-Rope Detachable) swivels are specifically designed for high-capacity applications where ease of connection is paramount. Featuring a 360° turnable housing, these swivels are compatible with common studless links and end links, eliminating the need for additional intermediate connectors.