Philips White SON® High Pressure Sodium Lamps produce warm, incandescent-like color with exceptional brightness and color rendering properties. Energy efficient: Three times the efficacy and five times the life of incandescent lamps. Excellent lumen maintenance: Long life and reliable stable color performance. Choice of ED-17 or T-10 lamps: ED-17 diffuse coated medium screw base lamp offers low source brightness for downlighting applications, T-10 clear lamp with PG-12 prefocus base provides precise optical control for accent and display lighting applications. Low ultraviolet output: Minimizes fading of materials. Rated for use in open fixtures.