Review on Enhanced SEO: Silent Hitch Pin Lock (Let's Go Aero SHP 2081 - Class I) by Adam Gray

Very satisfied after trial fit. One problem is that the threads bottomed out before the pin could push the bike rack stem against the socket. I suspect it depends on how thick your shaft is, and I don't necessarily blame the manufacturer; maybe you don't want to lengthen the thread and load the bolt into a scissors in the thread when towing? For a small load like a bike rack, that's not a big deal. I had to add two washers under the head to fill the gap and get the pen to work properly. I had washers but many don't, it would be nice if the pin came with them. I suspect if you didn't realize the threads had bottomed out and just kept twisting them to make them tighter, you would break them, which may have happened to the other reviewer. There are other products on Revain like this for class I couplings but from what I've seen they don't seem to be lockable. Basically I am satisfied with the price.