Aquabuy 10 x Air line valves - Air line tap - 4mm tap (1/2 turn type)
The taps are a half turn from off to full on using the control knob
They are suitable for air and liquids and give easy control by rotating the knob.
They cannot be turned too far as they are limited to a half turn giving excellent control from full on to closed.
Actual taps may vary from the one shown in the picture.