Gamma Seal Lids come in two parts. First, snap the outer ring onto the rim of your bucket with a gasketed seal. Then, the threaded lid easily screws onto this ring with another gasketed seal. These two polymer gaskets ensure pests and moisture are kept out of your storage container. Gamma Seal Lids are heavy-duty and built to last for years and years of use. If you make bulk purchases that come in large industrial buckets, you can use these Gamma Seal Lids to simply screw the lid on and off and keep your food protected with a good seal.