Packaging includes:1 Lock Pin, 1 Coupler, 1 Lock washer.
12.2mm bike trailer hitch coupler for Instep and Schwinn allows you to attach an
Instep or Schwinn bicycle trailer to almost any bike (such as all series AA, AB, AC AD, AE, AG, AH, AI)

There are vertical and horizontal holes on the trailer coupler, so whatever your bike
trailer coupler holes is vertical or horizontal, it works for you perfectly

With an additional trailer coupler attachment, both Mom and Dad's bikes can be
outfitted to tow the kids trailer, your kids will enjoy the bike ride. A bonus,
when your kids gets tired from riding, you can strap him next to your bike

The diameter of the hole attach to your bike is 1/2" & the outer diameter of the part
that attaches to the axle is 1".The diameter of the hole attach to your trailers is