I've already posted this in the "Rifle scopes for shotguns" thread. I've had the Tru Glo Tru Point sights on my gun for 5 seasons now and love them. The are all metal and the fastening system is ingenious. A nylon clip snaps over your ventilated rib and the metal sight housing hinges down over and in turn snaps over the clip. No magnets, two sided tape or external screws to loosen. I hunt hard crossing a lot of creeks and low crawling through woodpiles and brush and have never had a problem. They are adjustable for windage via a recessed allen nut.
What I like the best is the extremely low profile which allows you to keep your cheek on the stock promoting good shooting form and lending to their durability. My father has had several sets of higher profile Tru Glo's that were adjustable for windage and elevation both and he has either broken or knocked all of them off his gun. It's been my experience that you don't need an elevation adjustment for a 40 yard turkey gun anyway, unless your ventilated rib is warped. Just my 2 cents worth, these are tried and true.