They are completely useless . . . Brewferm make some that go from about 4.6 to 5.6 and good homebrew shops will sell them. . . .This is a reasonable digital meter . . . but as you can see expensive.
As for pH 5.2 . . .it's a phosphate buffer and in certain circumstances can rob the mash of calcium causing a lot of problems late on. . . . if you have a moderate amount of calcium and low alkalinity then it will work otherwise you are better using more 'normal' methods of controlling the mash pH
Those are the ones . . . they can be cut down the middle of the strip to double the number of tests that can be made.
Just be aware that these things depend on being able to differentiate a colour . . . and everyone's colour perception is different . . . Which, despite my photography work, is the reason I have a digital meter :lol: . . . . . And most of my photography is Monochrome :lol:
I've got the strip ones, but the pH 5.2-6.8 range one rather than the lower pH ones, on the basis that if you're measuring at room temperature, your solution will be a little more basic than it was at your mash temperature.