Combo track is self-cleaning and self-aligning. Its unique, flat top design imparts extra strength to the track, which eliminates deflection from heavy, rolling doors. It is made of 14 gauge, galvanized, high carbon steel that is roll formed to assure maximum uniformity over its entire length. Galvanized steel mounting brackets are projection welded on the top of the track at 2-foot intervals. It comes in standard lengths from 8 feet to 20 feet ( two foot increments. Longer track lengths mean fewer joints for stronger installations and smoother rolling doors.