Knot-a-Coupler Dog Leash Connector by Ruffwear. This twin coupler is designed to make walking multiple dogs easy and enjoyable. The stretch-rope construction gives just enough to give your dogs some freedom while retaining complete control, and swivels reduce twists and tangles. Features: – Reflective trim woven into the coupler improves safety in low light. – Couplers can be linked to walk 4 dogs – Combine with Knot-a-Leash for the ultimate multidog setup. Sizing: S: 12 in. stretches to 18 in., 7 mm thickness, dogs walk 3 feet apart L: 12 in. stretches to 18 in., 10 mm thickness, dogs walk 3 feet apart