ROBERTSON 5P10028 BLU0150A04900, Bulk-Pak of 4 HID Reactor mBallast Kits for 1 S55, 150W High Pressure Sodium Lamp, Pulse Start, 120Vac, 60Hz, NPF Equivalent to Philips-Advance 71A8107, Osram LU150/120R, Universal 1233154U001 Equivalent to Keystone HPS-150R-1, Hatch GS150ARNAK Also offered as a single indivudally packaged version by ordering ROBERTSON 3P10028 Commercial grade. Two year warranty. Go to RobertsonDirect.com for complete technical data.