PROTECTION AGAINST SCRATCHING. The soft, depressant surface is an efficient protection against the scratching of the rear (push rod) of your drawing vehicle or other vehicles. Shinbone protection. Furthermore both, the AL-KO Soft-Dock and the AL-KO Soft Ball, are an effective shinbone-protection, because the coupler of your hanger or the coupler-ball of your car can be overseen very easily. Soft-Dock for AL-KO couplers AK7, AK10/2, AK252, AK160, AK300. Soft-Ball for the tow-bar with 50mm ball art.no. 91385.