I was putting in some new hyper blue bulbs in my clear corners yesterday and was checking them out because of all the moisture talk on this site. My corners are not even sealed at the top and bottom, at least a 1/4" gap between the lens and the housing. I am assuming that this is to allow moisture to enter and leave without getting trapped. I have had them two weeks now with a few rains and have never seen a drop of water in them. I also have new rears which are sealed all the way around but they due have two weep/vent holes. One at the top and one at the bottom of each light. The weep holes also have little rubber elbow tubes on them I am guessing to prevent water from splashing in them some how.