ARK 3-In-1 Heavy Duty Coupling Base Plate XOCBPV4Ark have released a new XO Series Coupling Base Plate, that makes mounting of both coupling and trailer safety chains to the trailer quicker, easier and most importantly, safer than ever before. Safety chain attachment points are the means by which the safety chains are attached to the drawbar. These points must be located as near as practicable to the tow coupling. Where two points of attachment are required, they must be mounted one on either side