We're building a hydroponics system and need to measure the EC of the water. After searching in a lot of places, we finally found this product and ordered it along with the K1 probe and a temperature sensor. If you're going to use the Raspberry Pi along with it, buy a set of Qwiic to Female wires, it'll really help in quickly connecting the board to the Pi.
The source code works well out-of-the-box. The seller also calibrated the K1 probe for our use case before shipping. They have been very helpful all along the way.
The only gripe we had was with the USPS shipping, and this is no fault of the seller's. USPS packages to India are well-known for having bad tracking. USPS didn't show any updates after about 3 days, and the Indian Postal Service didn't show the tracking at all. Although, just be patient, and it delivers, eventually... Ours took 20 days to deliver. The packaging is really sturdy and strong.
All in all, if you're looking for an EC sensor, this is a great one!