The integrated telescoping arm features a structural crossbar to support larger pendants up to 20 pounds and 20" in diameter. Compatible with Line-Voltage Pendants that use Incandescent, Halogen, GU24 Compact Fluorescent and 4-Pin Compact Fluorescent Lamps. When using 4-Pin Compact Fluorescent Lamps, use the ballast that is included with the Pendant. Can mount to either a 4” square electrical box with round plaster ring or an octagonal electrical box (not included).