4 Foot 4000 Kelvin
Keystone's Smart Drive LED T8 lamps run on existing Instant Start and Rapid Start ballasts. Be sure to check the ballast compatibility guide to ensure these lamps will work on your existing ballasts!
Keystone's Combo Drive LED T8 lamps and Forest Lighting UniV8 lamps are Type D, meaning they can use the existing ballast and wire direct. Again, if you want to use your existing ballast you will have to make sure your existing ballasts are listed on the ballast compatibility sheet for the lamps. Also note Keystone's lamps are single-end power while Forest Lighting uses double-end power lamps.