The active ingredient is 55% aluminum phosphide. This solid form fumigant is packaged in tablet form, 500 tablets per aluminum flask, 14 flasks per case. Pellets are packaged 1660 per flask, 21 flasks per case. These flasks are closed with a gas-tight screw stopper, after removal of part of the container it can be resealed for further storage. Phostoxin® is a restricted use pesticid: for retail sale and use only by certified applicators or persons under their direct supervision and only for those uses covered by the certified applicator’s certification.