What Compression Tester to Get

That tester is fine, but I wouldn't get those fittings. They're a PITA trying to get them in and out and not leak. Use one like below. Decades ago they didn't have these so I made my own out of a spark plug and a 6" piece of pipe.  You want the 12mm.

https://www.aircraftspruce.com/catalog/topages/atscompressiontester.php?clickkey=4690

Hi Shaun,

Unless you are offering a professional service ie this is for your own routine (100 hr service) engine management the cheap (there are identical cheaper automotive units) tester will do just fine.

The main objective of compression and leak down tests, is to establish bench mark data (usually from the first 100-200 hrs). All future test will be compared against the bench mark & subsequent tests, to give you an idea of your engines "health" 

Using the same devise (your own) for each test, enhances the value of the data, even if the tester itself is not so accurate, as long as it gives consistent readings.

Note: Rogers advise regarding spark plug/tester access.

😈