I have a pair of the Ultra Mags. One of the bodies fell off. The return took waaay too long and I got a rubbish repair job. I ended up taking them apart and fixing them myself. A couple of people on here have the Nano's. Apart from the allen key fittings being shody quality they seem to be lasting. Superstar products are cheap for a reason.

very grippy!!! just be sure not to hit yer shin bone on them 
and currently have kevlar pads which again have been pretty hard wearing with no problems, for the price I would buy them again 

the last one is thoroughly boring, just watching a helmet float around a forest