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We do not sell a general drainage catalogue.

Backflow prevention is the whole business, and that focus is the reason the range covers what it does: five valve families, dozens of connection variants, and bore sizes that step in millimetres rather than nominal jumps, because real drainage pipes are rarely perfect. That specialisation shows up in the detail. Slide-direct models are selected on measured pipe outside diameter and grouped by pipe material. PVC, polyethylene, twinwall, clay, ductile iron and concrete each have their own table. Inline models are selected on measured bore, with +G gasket variants covering pipes above the standard range. Where a size falls between published models, we quote it.