Philips 321539 135-watt T15 SOX135 Low Pressure Sodium HID Light Bulb,Philips Lighting,321539" /> Philips 135-watt SOX T15 Low Pressure Sodium lamps offers high energy efficiency Long Life - Lasts up to 18,000 hours Vibration Resistant - Rough service arc tube support system provides protection against shock and vibration T-21 Shape with D.C. Bayonet Base Operating Position: Horizontal +/- 20-Degree