USG Durock™ Brand Exterior Tapes are specially designed to reinforce the joints and corners of USG tile backerboard panels. USG Durock™ Exterior Tape is 4" wide, and it is the required product for completely covering and reinforcing corners and joints of USG Durock® Cement Board when used as an exterior substrate. USG Durock™ Exterior Tapes are made of alkali-resistant glass-fiber mesh to provide a strong, long-lasting joint.