This is the most accurate Co2 controller I've every owned. It's been great since day one. It's accurate +-.2 degrees. No more big swings like my old controller.Yes I would recommend this 5 stars.Only 1 set of packages for calibration supplied (as per photo in ad), but no Electrode Rinsing Solution or Electrode storage solution. These are optional, so plan to spend more for the solutions required for calibration, initial use, storage, or DIY. I interfaced this controller with the Milwaukee MP 810 dosing pump, bought separately. Recommend buying the unit together for about $2.15. I calibrated the electrode, which was spot on out of the box, gave it a test run. Pump delivers 60cc/3 min. I put the pH probe, and PH solution delivery tube from the pump in my 45 gal hydroponic garden's reservoir. I diluted pH DOWN solution 1/4 cup/gallon of water, and put the intake tube and filter (float?) provided with the pump in the diluted pH down solution. Set the dial on the controller to about pH 5.9, and put the toggle on Below. Setup this way, the controller will activate the pump to deliver acid to the reservoir to keep the pH below 5.9. The pH was above 6, and the pump immediately activated and pumped a couple of ounces of the acid solution into the reservoir, then stopped. Unit is on and will monitor pH and deliver enough acid solution to counteract the tendency of pH to rise as plants use up acid nutrients. What a relief! No more tedious pH checks and estimated additions of acid to keep pH in desired growth range of 5.5-5.9 for the heirloom tomatoes I am growing indoors.I purchased this to use in a hydroponics system. I set it up with a pump to control my PH levels. The whole set up appears to be great and accurate. I don't have any other quality probes to compare with but my plants are healthy and the meter stays calibrated. I would recommend this and would purchase more in the future if needed. Been using for about 3 months now.I've used Milwaukee pH controllers for years and have never had an issue. This product arrived today and I cannot calibrate it. The readings are constantly jumping all over the place when trying to calibrate the unit using Milwaukee's calibration fluids (7.0 & 4.0). The readings then settle down at 0.0 or 14.0. The unit did come fully intact and no obvious damage - the probe was encased in a solution so it wasn't dry. The unit was sitting in my mail box all day at 90+ temps. It was very warm when I took it out. I've submitted an email to the Milwaukee support folks - we'll see what they say.UPDATE: All is well. Milwaukee replaced the faulty unit with a working one. It's working great! =)Have to say I was a little apprehensive to order this based on some of the comments, but very happy to report it works flawless...After calibrating the probe using the supplied fluids, I tested it against a reliable PH test kit and it was Spot-On.. I use this in conjunction with the Milwaukee CO2 regulator with great results...Since I didn't purchase the regulator from Amazon I will have to rate it here. - A lot of comments about the Milwaukee CO2 regulator are not good, but if you take the time to let the low pressure side break in a while "I let mine bleed into the air for 3 days prior to putting it into service" the pressure settles in nicely and the flow rate can be fine tuned with the valve rather than the regulator. It's running a 90 gal planted tank with fantastic results.This works extremely well on for controlling my CO2 injection on my 120g planted tank. It was easy to calibrate and install and is giving accurate readings so far after 1 week. This product gives real-time readings and has eliminated pH testing and that in its self is worth it to me. I have a timer plugged into the outlet that the unit controls. In my opinion, buying a timer with this is a must. It allows me to leave the product on 24 hours per day while letting the timer control the flow of CO2. I am able to monitor the pH at all times and evaluate the pH swings with CO2 injection. Currently, the pH is 6.8 in the AM before the CO2 comes on and it drops to 6.6 by the end of the time I have the CO2 set to be on. Works like a charm.Cumple su funcionSuper easy to set up, seems quite accurate, and having a constant monitor is very nice. No issues at all. I used a previous version for monitoring CO2 in planted aquariums and had great luck with that as well. Glad I chose to revisit this manufacturer. =)Works perfectly with my co2 system but if you buy this from amazon.com the American site you will have to swop the (110 volt) 12 v 500ma power adapter for a (240 volt U.K.) 12 volt 500 ma power adapter with the end plug you can turn to get the right polarity and a travel adapter for the socket that you plug you co2 intoSo have given 4 stars because the voltage supply is not universalOttimo prodotto di fattura eccellente e sonda molto precisa, le prime volte va controllato per poterlo calibrare al meglio poi va da Dio, consigliatissimoWorks great with CO2 system .. no need to worry about switching off the CO2 system ..