I tried one of these bits for the first time and it worked very well. I recommend using a drill with a handle, or at least getting a universal handle to get a better grip on it. Put the drill on slow rotation and lower the clutch all the way, because this thing can hurt you more than you think if it hits a rock. Chomsky appears to be the retailer as there is no brand name on the packaging. and they appear to be sold under different names elsewhere on Revain. That said, this price is as good as any and my package was delivered on time so I would have no hesitation in ordering from Chomsky again. I just wish it included a bag for storing the drill bits and not some silly looking gardening gloves that I'll probably never use.