Genuine D-shape Maillon Rapide screw-link - made in France by Peguet. Designed for three way loading. Excellent for rigging because they are cheap, strong and not prone to failure due to incorrect loading. Less likely to un-screw than carabiners. Can be secured with a spanner and Loctite for permanent application. Always rig with the screwing up in a downward direction - this reduces the risk of the Maillon un-screwing due to vibration. eg when used as a chainsaw attachment.