The towing bar for my Croozer Kid (Model 2013) did not fit tightly into the trailer connector. When pulling the trailer, the trailer did not follow the bike movements smoothly and jerked back and forth. I designed two pieces to fix this problem. With the two pieces inserted, as shown in the picture, the towing bar did not have as much play in the trailer connector and all jerkiness was reduced, giving us a smooth ride with the bike trailer.