If you have an older style Adam’s Trail-A-Bike with a 12mm square hitch (model year 1997 and earlier) and you want to use the new and improved Block Sleeve Hitch, you will need to retrofit your old trailer using this Stepdown Block. The Stepdown Block must also be paired with a 1st Knuckle in order to complete the retrofit to use the new hitch style. If you have an older trailer, you will be glad you did the retrofit, as the new hitch is much stronger and stiffer than the older model hitches.
To determine if this is the correct size for your Adams Trailercycle, measure the opening at the toungue. If the opening is 12mm this is the correct block. If the opening is 15mm, see the Adams Trail-A-Bike Hitch Block and Bolts.