I bought too many of these from LED Wholesalers. I turned this on to make sure it worked properly but it has not been used. This bulb is very bright. You can barely look straight into it. 168 leds mounted on a mirror for reflection. These run cool and efficient. People are debating the use of LED's for growing but I can tell you from experience that they work really good. Screws into a standard base. 4.75Ø x 4.75 high. Buyer pays shipping. Paypal please. Good luck!