Syringe Filter Ring for Gas Pycnometry

This small ring is used to hold a circular filter in place at the bottom of a 100 mL syringe. The syringe is being used to measure the volume of a sample using gas pycnometry, as described here:

https://quantitativecafe.com/2022/01/10/measuring-density-with-gas-pycnometry/

The ring and filter allow us to measure the volume of ground coffee, which would otherwise find its way through the tip of the syringe and into the pressure gauge.