Wasn't sure about this thing when I pulled it out of the box. It was light and very "plasticky," it felt like a toy. So I took it to my basement, held it against the tile floor (which is laid over solid concrete) with the knuckles facing up, and whacked it a few times with a hammer. No cracks and no bending. The worst damage was a few small scratches and dents. I then used them to punch that same floor. Some scuffs on the corners, but no real damage. These are definitely the real deal.

The only fault I could find is with the design, which isn't specific to these knuckles or even only to the knuckles on this site. The design puts too much pressure on the pinky. So I recommend that if anyone were to need to use a knuckle duster, they remove their pinky from the hole and place it on top of the knuckle, in between the groove. This pushes the index and middle fingers forward, which focuses the punch on the strongest fingers and keeps the rest out of the way.