Festo Push-in Y-Connector 4mm to 3mm - www.aeropanda.com
Festo 153319 QSM-M7-4-I Push-in Fitting, Nickel Finish, 3.1 mm Inside Diameter Minimum Order Requirement 10 / Order in Multiple of 10: Amazon.com: Industrial & Scientific
Festo 215130, 215131 Multi Connector 20 Pneumatic Line Connections | eBay