Bluelab PENPH pH Pen Fully Waterproof Pocket Tester, Easy Calibration, Double Junction Probe for Improved Accuracy and Durability https://www.amazon.com/dp/B005POOJHG/ref=cm_sw_r_cp_api_glt_fabc_TTEH3A6XC5VKH8DZAYVH?_encoding=UTF8&psc=1

This is the one I have. You definitely can’t skimp when it comes to digital ph pens. I’ve been growing marijuana for years and have used this pen the whole time and have zero complaints. If anyone is looking to pick one up this would be the one I recommended.