Top positive review
Choose the one that looks like it will work with your trailer.
Reviewed in the United States on January 17, 2021
I got an instep Kiddo trailer 2nd hand and it didn't come with the coupler.
I looked at the diagram here, and I talked to 2 different people from instep, and they both suggested the flat coupler based on the model and date code information on the trailer. I really didn't get it, because the trailer arm obviously comes in at a 45 degree angle to the bike, not 90 degrees.
So i disregarded the advice of the people i talked to, and ignored the pictures on this listing telling you how to choose the right coupler and just got the angled one. It worked out perfectly. I still don't understand in what world the straight one would be a better choice for this trailer. Maybe mine is a fluke, or maybe I'm not using it right, but ive got on 2 decent rides and it works great. I would have had to bend the spring quite a bit to get it into a flat coupler.
Anyway, besides that, its easy to install, sturdy, and works great. I used it on a 29" Trek Xcaliber mountain bike and it fit like a charm.