I put a couple of hundred of the new type plastic excluders (Dadant sells them,I think they are made in Greece) on hives this year.The bees were a bit slow to go through them till they got some wax on them then they were fine.They were comparable to the metal excluders as far as the amount of honey in the supers.I really hated the old type plastic,but these are a great improvement.Now if I could just figure out what the ad means when it says 'easy to clean'???