I have heard that they are not. I have done pH testing the manual way with strips. They are extremely cheap, simple and accurate.

Any probe that looks like this is usually shit.

PH strips are easier and accurate enough for what you need.

I purchased one of these thinking it would work.

It doesn’t, it’s garbage

No. I’ve had a similar one that, even when I stuck it in a glass of water, went no further than “lightly moist” on the indicator. Worthless.