UEi Test Instruments EM201SPKIT Static Pressure Kit - HVAC Airflow Measurement Tool for Duct Testing, Balancing, and System Diagnostics

You can find cheaper pressure meters, but I wanted something with good accuracy and resolution from a known company. I am very pleased with this unit.The build is solid, and the operation is quick and easy. It even read 0.000 when I turned it on (didn't have to zero it with the button). I was also able to change to in-wc units without reading the manual ;-)To understand the filter pressure drop (I plan to put in a MERV13 and want to understand the fabled stress this may put on the blower), I took measurements on my HVAC return plenum and just aft of my filter before the fan. So far, I just did this with one port, leaving the other open to the air. Got reasonable results from both locations. I may use the static pressure probes later to see if that makes a big difference by tapping into the air flow better...There was s slight drift after removing the tube from these negative pressure locations, but the drift was well under the value of the smallest pressure and it returned to zero in about 15 or 30 seconds.Subtracting the two readings gave reasonable results for the filter pressure drop relative to what I would expect, so I have no reason to question the readings beyond the drift uncertainty. Any errors are mine - due to not having used the static-pressure probes (didn't want to drill new holes right now).In summary, I am very impressed with the quality and usability of this unit. 5 stars for sure.