Bought this nylon hammer for my jewellery making but discovered to my surprise it imparted concentric rings onto my silver, because the flat end probably was not finished off to a smooth finish and had these slight concentric rings on the nylon, most likely due to the mould making processes. I could not be bothered to return the item, so I tried hammering it on a hard flat metal surface or even ironing it to smooth the rings off but to no effect, however using a very fine file managed to smooth the flat end nicely. This is just to warn other jeweller to check theirs is ok and to just smooth it off with a fine file if you have the same problem.