Review on DECKAS Chain Guide BB Mount: Lightweight Aluminum Alloy Bike Chain Guard for MTB Bicycle with 30-40T Compatibility by Steven Hudson

I converted 2x10 to 1x10. My chain was coming off so I figured it would work with my setup which is 11-50t and a narrow 30t width up front with a Shimano XT MT-800 BB. 30t is too small as the chain guide will rub against the four bolts that attach the chainring to the cranks if you try to install the guide as directed. The guide itself and the seals are ordinary plastic, but in case anyone is wondering, everything else is metal. I'm sure if I had 32t or more it would work fine. I hope my configuration helps you decide if it's right for you.