OK--I have had this unit for only one day, however I am so impressed that I am writing a review earlier than I usually do. I ordered the 40 watt --1  acre unit and that may have been an overkill as the Stringer I am replacing is far smaller. I am switching to the Flowtron due to the high price at the local hardware for a replacement bulb for the Stringer. I note the replacement bulb for this unit is less than the Stringer by several dollars and is three times as powerful.