Achilles Pencil Pressure Gauge provides a very easy, convenient method of checking the pressure in tube chambers. This gauge can fit into the top portion on a Achilles valve, with the rubber mold providing a tight seal. Due to this tight seal, no air will escape while checking the pressure. The stainless pin sticking down will move aside the valve diaphragm, allowing the pressure of the tube chamber to be reflected in the pencil gauge. This gauge will work on all Achilles valves (with exception of SU series and Riverboats), but is not recommended for use on Achilles air floors due to the high pressure.