I have purchased several of these over the years.  They are the most durable, strongest, and effective zappers I have come across.  I have tried several models and brands.  These work the best.  I live on 3 acres on a lake in Texas.  We have airborne bugs of all shapes and sizes for 9 months out of the year, and two swarms that last about 3 weeks each.  This thing does the job and all I do is hose it off occasionally during the swarming.  I have found piles of dead bugs under this thing during the storms that will fill a plastic shopping bag daily.  Incredible construction and I live mine exposed to the elements all of the time.  No covering or roof to protect it from rain, sun, snow, or ice.  These things last for years.