Our <b>CRL Double Roller Track System</b> is beautifully designed to be both attractive and functional. Everything you need to install sliding glass doors into a showcase or cabinet is included. Just cut the Upper Channel and Lower Track to size and it's ready-to-install. <br/>Smooth operating nylon rollers are spaced every 4" (102 mm) in the Lower Track, which has been pre-drilled with holes for securing it to the base. The Top Channel is easily set into place above the Bottom Track, and can even be used as a side jamb to provide a full surround frame for the glass doors.<br/><b>NOTE:</b> Designed for use with 1/4" (6 mm) tempered glass, the maximum recommended panel size is 60" (1.52 m) tall by 30" (792 mm) wide, or a ratio of 1.5:1. Recommended minimum overlap of glass panels is 1-1/2" (38 mm). <br/><b>General Glass Cutting Guidelines:</b> Glass Height = Opening Height minus 7/8" (22 mm).