This is a small funnel with a 1/4" NPT threaded output.

I needed this funnel to introduce liquid product into the common 1/4" quick connectors found on air tools.

In my application I have a 1/4" coupler connected to a steam boiler. When I need to, I can connect a pressure gauge to calibrate or check on the vaporstat. Being able to disconnect the (expensive) gauge from the boiler saves the gauge, but it make it difficult to put additives into the boiler to prevent rusting, foaming, pH balancing, etc. So this funnel solves that problem.