My 300w wonderlight is NOT so WONDERFUL any more. Purchased in January, began using this bulb in mid May, not working and its been used less than 90 days. Product works but how many units are defective and will prematurely stop working before the rated 10, 000 hours +???....the product has a weakness, its filament is not of a quality that stands up to the products long term application, as stated, in my opinion. Fortunately it is covered by warranty, but at a cost to the plants, my day, time and effort, not to mention the return process and what to do with my plants because its Saturday morning. The plants will deteriorate by the time the new light arrives, not good. I am skeptical if these bulbs can actually perform for the rated hours they claim they will.