This is a pack of 4 mirror holding brackets or clips with full disk type that can be used to wall mount a mirror or glass up to 6 mm. 
There is no need of drilling holes into the mirror. 
Its a DIY type of clip which requires screwing the lower bracket to a wall or wooden surface and then fastening the top disk bracket with the mirror in between, It also consists of a rubber washer for mirror surface protection and grip.