The DEWALT Air Compressor Monitoring System monitors the run-time of your air compressor, as well as the passing of time, and alerts you to required maintenance using an app on your Apple or Android smartphone. It doesn't require any electrical or mechanical connections to your compressor other than being physically attached to it with the included hook and loop fastening tape. The unit comes in the kind of slick retail display packaging that DEWALT customers have come to expect. This is no cheap cardboard box! Opening the package reveals the unit itself, self-adhesive hook and loop fastener material (to affix the unit to the compressor), an alcohol prep wipe, and a really skimpy instruction sheet. Also included were three Chinese DMEGC brand AA cells to power the unit; I would have preferred to see name brand cells like Energizer, Duracell, or Rayovac. I used the DMEGC brand with some trepidation. To install or replace the batteries requires removing six(!), small phillips head screws to remove the entire front panel, giving access to the battery holder (admittedly a nice one). There was no included screwdriver, but there should have been since that's not a typical tool for many people who rely on large compressors. Be careful when reassembling the unit as there is a very thin rubber seal in a groove around the edge. The associated iPhone app is quite extensive, giving the user the ability to choose a DeWalt compressor, after which all of the maintenance intervals, based on run hours and calendar months are automatically filled in. Don't worry if you do not have a DeWALT compressor -- you can also manually enter your own compressor make, model, serial number, and maintenance intervals. The maintenance items are fairly extensive and include things like the belt tension, fastener torque, pump oil change, and pump air filter. The iPhone app is pretty good, but it has the kind of idiosyncrasies one would expect for a limited audience, specialized app. I won't go through all of the little things I found. But, for instance, what if you don't care about the electricity cost to run the compressor? Too bad. The app still requires that you enter the average Kwh cost when setting up a compressor, and the app give you an example with a dollar sign in front and then complains if you enter the dollar sign, saying it wants just a number. No deal breakers here, but just don't expect something as polished as a mass market app with millions of users. I'm happy to report that the app provides a device battery percentage bargraph, allowing me to keep an eye on those DMEGC brand AA cells. A feature that is missing is the ability to define custom maintenance items and the maintenance intervals in run hours and calendar time (with that, one could easily add a battery change reminder). For example, if your compressor's manufacturer, or your organization, requires that certain compressor checks be performed at certain intervals, this won't be of any help. Think of things like air pressure setpoint checks, tank pressure gauge calibration checks, external filter condensation drain, and general cleaning of the motor and unit. It has what I most wanted; a tank drain reminder. But it's nearly worthless for a home user like me as it's not based on run time. If the notification is turned on, it reminds you to drain the water out of the tank every day. It doesn't matter if the compressor has run for five hours that day or whether it hasn't come on, or even been powered, in a week. Most home users, who only occasionally use their compressors, will likely become numb to the reminder after it tells them, day after day, to drain the tank of a compressor that hasn't even been run. All communications with the smartphone is over Bluetooth. And therein lies one of the biggest limitations. This requires that the smartphone be physically close enough to the compressor monitoring unit to establish a Bluetooth connection. There's no WiFi at work here, so if you are an industrial user responsible for multiple compressors, maybe even in multiple buildings, you would have to physically walk from compressor to compressor to establish Bluetooth communications with each and see what items were due for maintenance. It's probably more practical to just have scheduled maintenance that you do on a calendar basis with the help of a simple hour meter on each compressor rather than something as complex as this. Fortunately, most of the shortcomings are something that DEWALT can fix with app updates -- and I really hope that they do! As the product stands now, it's neither fish nor fowl. It lacks features needed to satisfy either a home user with one intermittent use compressor or to work well for an industrial user responsible for maintaining multiple, heavily used compressors spread out throughout an organization. Not a bad product, but could be improved.