Hey. There are two types. One with a built in dimmer that simulates sunrise and set and one with just the 4 end caps. If you use a timer for all your electricity you just want the regular one as it will be tough to synchronize the sunset mechanism and your timer - you only get a few options like 10 12 14 hour. Also the regular one is a bit cheaper. Great fixture and external ballast is much better. I don't use a housing, just bare bulb but my friend has covered his with a slat from venetian blinds.