Ancol Training & Safety Nylon Coupler. The Ancol Nylon Coupler is a robust and reliable tool for walking two dogs at once. The sturdy nylon is weatherproof and long-lasting. The coupler has a large O-ring so it can easily be attached to a lead. Couplers are a must-have for pet owners with two dogs. While walking two dogs used to mean leads, dogs, and owners got tangled, a coupler means just one lead is needed and the dogs are kept together. The length of each of the Nylon Coupler leads, including the trigger hook, is 30cm (approx.). The maximum recommended weight for this coupler is 2x50kg.