Thank you all for help on "mite screen". I have some and am building the board today. Today I am also wondering what " Plastic frames "are. I am using Permadent on wood frames both for honey and brood boxes. As you all know, Permadent is a sheet of indented plastic with a bees' wax coating on the outside. My bees build Permadent foundation into very nice drawn combs. I tried a full California made plastic frame ( I can not remember the name of the manufacturer ) during my first beekeeper life about 15 years ago and the bees would not build them up evenly. Have The plastic frames been improved so that this will not happen again? Is there an introduction procedure that enhances sucess? Please advise as I don't enjoy nailing frames together. Thanks again for all the good advise on Bee-L.