Product Description. HD105-120 Step down 120 Volt to 12 Volt 105 Watt Electronic Low Voltage TransformerFor use with 12V Halogen lights, Under-cabinet lights, Recessed lights, Track light, Landscape light and other similar lighting system ONLY. Dimension: L- 4 1/4", W- 1 3/4", H- 1 1/4" Center hole: 3/8" diameter pipe Also .