Thanks for the reply. I have 17 four foot units with two tubes each in my 600 square foot garage. 10 years old and no failures. The LED’s do interest me.Why Fluorescent? Most shops I've worked in during my career had Fluorescent lighting & it was terrible especially when the fixtures (Ballast & bulbs) get old. I'm running Philips Day-Brite LED 4' 5100 lumen Vapor fixtures in my shop & they blow any Florescent fixture I've ever seen out of the water, I like the Vapor type fixtures because the Diffuser clamps on & it's sealed so insects don't get in.