PAL Evenglow 64-PAL-SRL-CW 5" Cool White Sonar Retro Bulb is made from high performance engineering plastic with thermoplastic for heat transfer and 40% glass for greater strength. Providing more resistance to thermal shock than glass. Adjust the color temperature from 2700k-6500k to make the white light you want. Choose the light with excellent resistance to most swimming pool chemicals and industry leading optical diffusion and light efficiency.