The surface of these brackets must adhere to a clean, dry, flat surface. If the surface is too rough or bumpy, it will not adhere evenly across your mounting surface which could create a weaker hold. The No Tools brackets can adhere to many different surfaces such as wood, metal, concrete, vinyl, and glass. 

While this product is meant for permanent application there is a way to remove the brackets without damaging the frame. Using a hair dryer to help loosen and break down the adhesive will allow you to remove the brackets. Any residue can be removed gently with a putty knife or an adhesive remover such as Goo Gone. Once removed, the No Tools brackets can no longer be used and a new set of brackets will be required.