Series 5 fiddle blocks offer small to medium sized racing and cruising yachts an ideal solution for mainsheet and boom vang systems. Black hardcoat anodized aluminum with Delrin sheaves. These are dependable blocks that will reliably do their job day in and day out. Sheave diameter: 2" Pin diameter: 1/4" SWL: 1,750 lbs. Maintenance: flush with freshwater periodically