I used a set of these frames, in black, last season (2006). My impression: you could probably drive over them with a vehicle and still use them (extremely durable); only 9 of them will fit in a 10 frame super - the end bars are that wide; as with most plastic the bees were reluctant to use them, at first, but once they did, they filled them fast and well. I never found any brood in them.