Neck connectors are beta straps with a key shaped slot to attach to the McKinney hook or water hook on your harness saddle. A loop at the end allows the check rein to slip thru. Available in 5 sizes — Mini, 5/8″ wide Pony 5/8″ wide, Horse, large Horse or Draft 3/4″ wide. Black is in stock. Other colors are made as needed.