This window track is ideal for window glass or for installing sliding cabinet doors. Each channel groove is slightly (.005") narrower than 1/4" window glass so there is positive pressure against the glass at all times. It seals out leaks and prevents glass from rattling. Made of B-FLEX marine plastic, it will not crack or discolor. The elevated slide at the bottom of the channel makes windows or doors easy to open and close. Sold in 8' lengths. White.