ROBERTSON 3P10057 Individual mHID, 50 Watt, S68 High Pressure Sodium Lamp, 120Vac, 60Hz, Normal Ballast Factor, NPF, Model BLU0050A04900 M (Replaces Model BLU050A04900) Equivalent to Philips-Advance 71A7807, Osram LU50/120R, Universal 1233-251U Equivalent to Keystone HPS-50R-1, Hatch GS50ARNCK Save by ordering the Quik-Pak of 4 individually packaged ROBERTSON units 2P10057 Take advantage of Robertson's 60 years of electronic design and quality manufacturing experience. Go to RobertsonDirect.com for complete technical data.