The quality of the light they do produce is poor and looks more like that produced by a florescent bulb. They are dimmable but they start to flicker a lot! Save your money and get another brand.
Easy to install, no delay in start up, the bulb comes on with no flickering. Nicer to have the bulb in an overhead fluorescent fixture than as an lamp on a desk. My birbs are happier now and their feathers have perked up again.