Over the years i have used many compression testers. My first tester looked like a large tyre pressure gauge but cheap which was a priority at the time. It did the job or at least i think it did.
The second one i got at least had a proper gauge on it but you had to hold it firmly over the plug hole whilst someone else turned the engine – so was always a 2 man job.
I had to buy a third when the second one would not retain it’s reading when the engine stopped cranking. It was the best of the bunch and combined the best features of the previous two.