wellthe bennefits of being water proof are,well the fact that its water proof sooner or later your going to drop your pen into the bucket that your mixing your nutes into,trust me it will happen.i dont think i have met a person yet that has not done it.umm hm digital has 2 hand held pens that are water proof the TDS-3 and the comm-100 i have never used either of these.i use the cheap hanna 20 doller primo and it works fine. look around the net.your not really saposed to put links to other companies and what not.remeber when u do get a tester to get a couple of small packages of calibration solution.