Mounting Bars: Galvanized steel, 0.048"; pre-installed telescoping bars extend from 20" to 30" long and lock securely into position. Built-in locking tabs provide attachment to common T-bar systems. Self-centering feature simplified installation in 24" on center grid systems. Attaches to steel or wood joists without accessories. Frame vertical adjustment mechanism accommodates mounting to virtually any ceiling system using pre-installed mounting bars, or 1/2" EMT tubing (by others). Single locking features secures all adjustments. Alignment holes and markings allow fixture to be pre-set prior to installation. Final adjustment can be made from below, inside fixture.