The Flowtron seemed to be the zapper with the best reviews out there.  Consistently better than the other brands.  Some people seem to have issues with these, but I haven't had any.  It seems like with most reviews most of the negative comments are people just using the things incorrectly, others just have bad luck.  I installed this with the Flowtron pole.  It is like a beacon in the night.  Kind of neat and adds to the ambiance of a backyard BBQ.  It works great you hear it snapping a way, then occasionally you'll get a huge moth or something that gets in there and just lights that thing up. You'll see smoke and sometimes a little flame.  Sometimes they stink.  I'm not sure why some people don't notice hardly any kills.  After you plug it in, you don't get instant kills, it takes a bit for bugs to get confused and start heading toward it.  But after about 20 minutes of it being on you start getting kills.