I many years ago worked for SASSO Air Conditioning in Lake Worth, Fl.
I started using a H-10
Sasso would get calls from other HVAC companies because they were not able to find a small leak.
I would be sent and I would always find the leak.
I would tell the customer I can find a leak as small as 1/4oz per year leakage.
I am still now using my H-10 and would never use anything else.