Face Mask Great Dogs in a Row. Reusable Cotton Face Mask,. 4 ½ X 7 ½”. These masks include a PM 2.5 filter and an extender for ease of wear. This helps when you just want to pull your mask down for a moment. Our masks stack multiple layers of soft 100% pre-washed cotton. The CDC has adopted a safety-first policy and is recommending everyone wear non-medical protective face coverings to help "flatten the curve".