UNION TEE/BRASS/ Tube to Tube to Tube, 3/84 inch outside diameter. 264P06Poly-Type Brass Union Tee | Fits 3/8-inch TubingPoly-Type Flareless tube fittings have reduced a installation time when compared to regular compression or flare fittings — just push in the tubing and tighten the nut. No wren..