Based on this product's specifications, here are some alternatives and similar models
Adjustable Dog Coupler Chaba DWÓJNIK L 2.0/51–88 cm, red
Summary description:
Chaba DWÓJNIK adjustable dog coupler, size L, with 2.0 cm width and adjustable length from 51 to 88 cm in red. Designed to connect two dogs to one leash, it features sturdy hardware and reinforced stitching for everyday walks. Suitable for medium to large dogs, it helps manage paired walking, training or multi-dog control in urban and outdoor environments.