Doff Slug & Snail Killer MAPP 18982 PCS 06422 is a Ready to use bait containing 12.5 g/kg hydrated ferric phosphate (technical) [at least 9.79 g/kg anhydrous ferric phosphate]. About Doff. Doff Portland Limited, founded in 1946, is the UK’s largest independent manufacturer of insecticides, weedkillers and garden care products.