The Aqua Medic Reducing T-Piece is an ideal single-piece solution for tapping a 1/4" (6mm) outlet from an existing plumbing run. The 1/4" (6mm) outlet is ideal for 1/4” tubing, like R/O line, for supplying water to low-flow filter accessories like Nitrate Reductors and Calcium Reactors. The Reducing T-Piece is available in 3 sizes to ensure a clean installation into your plumbing scheme. Three Sizes Available for: - 1/2" I.D. Tubing - 5/8" I.D. Tubing - 3/4" I.D. Tubing All 3 fittings reduce to 1/4" O.D.