Oakton tdstestr4

I just purchased an Oakton TDSTETSR4 from Ebay. It was used and came with no instructions. I got it for 29.00. I am confused about the readout, it reads out in 0.00. I am wondering how this equated to ppm? Also, do these units need calibration? If anyone has experience with this type of tester, please let me know.
Thanks

I'm guessing more info/pic would help a lot . . . I, for one, have zero idea what this is?

Here is a pic of it.

Is that some kind of vibrator? LOL . . . still clueless. Guess this items use is for a method beyond my experience. Good luck!

I havent been able to find the vibrator function yet. I will give it to the little woman, if its on there, she will find it...LOL
It is a waterproof TDS tester, I also have a water proof ph tester that looks the same, no vibrator function on that either.