PROVA-MAT is a low perm waterproof membrane made of durable polypropylene that is ideal for creating fully waterproof and vapor tight protection in areas such as showers, bathrooms, laundry rooms, backsplashes, countertops and more. Install using Premium Modified Thinset and a 1/4 in. x 3/16 in. V-Notch Trowel. Do not use premixed mortar for installation of PROVA products.