These plastic classifiers are a must have for the gold panner and rock hound alike. For use with gold pans and 5 gallon buckets. Classifiers are used to separate larger waste gravels from the material to be panned or run through a sluice box. It is made of rugged green plastic, fits perfectly on 5 gallon buckets, and has 1/2 inch openings. For smaller screen openings please see our Keene and Jobe steel mesh screens.