These Constant Heat Hand Held Crimper Sealers make sealing portable. They are easy to handle and are quite lightweight. These machines work best on Cellophane, thick Mylar, and Aluminum bags (such as Coffee bags). We always recommend that you get a test seal done before you purchase any sealers. Doing this will ensure you get the best sealer for your job. These machines are not recommended for Polyethylene or Polypropylene material.