I trust this brand because I used their respirators before, and they are very good quality and effective. Unfortunately, these ones are a bit too big for the size of my face and are uncomfortable to wear, make my glasses steam up, and are ultimately ineffective because they don't adhere to my face the way they should. The box doesn't provide any indication of size, so it's not the seller's fault. I would recommend that people go to a shop like B&Q to try one on, and if it fits get them in bulk cheaper here. A box of 10 is good value for money and competitively priced.