HOLT ALLEN-Halyard Lock and Hook Racks. * Hole size(mm):4 Imcrements(mm):12.5 * No.of adjust.:5 * Length(mm):85 * Weight(g):15 * Max wire dia.(mm):5 * Designed to reduce halyard stretch and mast compression the Holt Allen halyard lock is used on many single handers such as Europe, OK and Finn. Anodised alloy hook racks provide a light and effective way to hold wire under tension giving positive location to take whatever sailing loads are applied.