Depending upon the type and concentration of contaminant and length of service time required, MSA offers 3 canister models, including Type N or Super-Size, Industrial-Size and Chin-Type. Canisters are seamless to prevent leakage or channeling of gases/vapors past the chemical sorbents, kept fresh by sealing tape on the bottom air intake, which also prevents moisture from entering canister before use. Easy to use and store because of compact oval shape. Labeled as to type and limitations. Color-coded for fast and accurate recognition.