Qualkem Box of 10 x 1 Litre 40 Shot ECO GREEN Cassette Fluid. A unique environmentally safe cassette toilet fluid developed to be Biocide free, Enzymatic free & Probiotic free, making thisthe first on the market to make this claim. We have also removed the dye and given it a fresh floral fragrance all from a 20ml dose in the waste and 5ml in the flush.