IsoLight™ Mortar is a lightweight, latex modified mortar that protects tile from up to 1⁄8" (3 mm) substrate cracking from in-plane horizontal substrate movement. Its unique "lightweight" formula provides 50 lb. coverage in a 30 lb. bag. Formulated with Easy Trowel Technology™, IsoLight Mortar provides superior handling and extended open time as compared to regular mortars, improving speed and productivity.