[Product Information]

Diameter: 6.69" and High:5.9".Direct Replacement Screw Fitting Underwater Pool Light Bulb.COMPATIBILITY: Hayward Astrolite"SP058 Series,Pentair Amerlite 784 Also as others have pointed out, when replacing your old light it's a good idea to put in a new gasket as well.
This bulb is able to lit up 25000 gallon pool,And as a bonus burns up a lot less electricity in the process.Works for most Pentair Hayward Light Fixture,no controller need,simply flip the power switch on and off over and over in order to change the light color mode. Please be noted,single red mode only 13 watt,not as bright as blue or other color.
It is a direct replacement (standard screw-in), 35Watt pool led bulb with a lifespan of +65,000 hours. It comes programmed with 16 settings including 7 solid colors and 9 beautiful and unique color "shows".It is the perfect light for medium sized swimming pools and typically used as a replacement for 500w (or lesser) standard lights.
Led light source: 441PCS SMD3014 RGB LED Chip
High quality and brightness LED source,Over current protection,Life span 50000 hours