Amazon.com : 1/2 to 1/4 Inch 4-Way Barbed Fitting,Irrigation Tubing Variable Diameter Connectors,For 1/2 Inch (OD 0.620 in.ID is 0.520. in)Irrigation poly tubing And 1/4 Irrigation tubing(10 Pcs Blue) : Patio, Lawn & Garden
Polyethylene T-Type Barbed Tubing Connectors (Tee-Shaped), Three 3/8 Inch Barbs,(Pack of 10): Amazon.com: Industrial & Scientific
Amazon.com: PureSec 3/8 Water Line Fittings 3/8 Push to Connect Fittings for 3/8 OD Tubing(3/8 Ball Valve+3/8 T fitting+Y+L+I, Pack of 10) : Industrial & Scientific
Jaco ® Run T Connector For Poly Tubing In Water Filter Systems
1/4" to 3/8" Polyethylene Quick Disconnect | U.S. Plastic Corp.
T-Connector Tubing Fittings, Polyethylene, 3/4" HB x 3/4" HB to 3/4" HB, pack/10