Norgren Pneufit 100230604 Straight Reducer/Expander - Stem O/D 6mm...

Norgren-Pneufit-10023-Series-Reducing-Expanding-Connectors-Norgren-100230604-p-This-stem-to-hose-straight-reducer-expander-fitting-has-a-push-fit-design-that-is-simple-to-use-and-provides-a-positive-hose-anchorage-with-a-strong-and-leakproof-connection-p-Norgren-Pneufit-100230604-Straight-Reducer-Expander-Stem-O-D-6mm-Hose-O-D-4mm

Price: 4.12 from Rapid Online Rapid Electronics Ltd.