Airbrush Air Hose Connector 1/8th BSP Female - 1/4 BSP Male x 2
Airbrush Air Hose Connector - BSP stands for British Standard Pipe thread.
This is the pitch, width and depth of the thread on the pipe.
You not only need to get the right diameter but also the correct thread type to couple to it.
A 1/8 fitting is commonly described as a 1/8" fitting which is not exactly correct as the diameter is approximately 9.35mm (approx. 0.37 of an inch).
1/8 is the most common airbrush air inlet and air hose size.
A 1/4 BSP fitting is commonly described as a 1/4" fitting which is not exactly correct as the diameter is approximately 11.75mm (approx. 0.46 of an inch).
This connector can be used to connect a 1/4 BSP Female outlet to a 1/8 BSP Male inlet.