KGL DL – Dual Locks (Mainsail & Top Batten) for Large Yachts The KGL DL is a 2-in-1 headboard car combining: a powerful mainsail lock (from 5 to 50 T depending on the model), and a gaff lock that operates on a single halyard, which, by definition (as a mainsail hook), is not under tension. This high-end system is designed for large yachts from 50 to over 200 feet. For this kind of equipment, every project is unique.