I have a pvc pipe frame that hubby made for me after seeing the q snap. I asked that it not be quite as deep. Not sure how he made the "snap" parts. I only know he did a lot of grinding to make them smooth. They do not have the ribs, and I haven't had a problem with them slipping. Maybe they are tighter than the q snap? anyway, I really like it. It is small, and very light weight.