If you’re serious about running, you know how important it is to listen to your feet. Seemingly insignificant running habits can have a big effect on your health and performance. Personally, I’ve had a lifelong battle with overpronation that has led to numerous injuries. No, I’m not smart enough to realize that on my own — I worked with a trainer some years ago who deduced that was my problem. But a trainer may not be readily available. A sensor that slips into your running shoes, a NURVV kit is like having constant access to a coach and physical trainer, delivering key metrics and analysis. It’s usually $300, but from now through April 9 you can get the NURVV for $210 — a full 30% off the regular price, no special codes or coupons needed.

The NURVV puts 32 pressure sensors under your feet — 16 on each foot — in the form of insoles that slip into your existing running shoes. While you won’t feel them, you will see them, since the insoles are connected to a module that clips to the side of your shoe. That’s where the NURVV’s brains, GPS and battery reside. It all connects to a mobile app that synthesizes the data the NURVV collects and gives you a detailed analysis of your run. The system collects your footstrike information and uses it to develop a detailed profile of your running behavior, including cadence, stride, pronation and balance.

You can really geek out on the wealth of data that the NURVV provides, or just scan the high-level recommendations. You get an overall heath score, for example, with a trendline, as in, “Your health has recently declined.” (That’s something it recently told me, because as a machine it doesn’t care if it hurts my feelings.) Like a good trainer, the NURVV will make suggestions about your training load, such as how long you should run tomorrow or if you need a rest. It recognizes problems in your pronation, cadence and balance and recommends ways to fix your problems.

And the NURVV does more than deliver post-run recommendations. If you like, you can even enable a real-time coaching mode in which the NURVV will advise you throughout the run, keeping you on pace with notes about your stride and cadence.

As a lifelong runner who admittedly has a veritable grab bag of bad running habits, I found the NURVV’s efforts to help me run faster while reducing injuries to be an eye-opening experience. This way I can get practical and seemingly accurate advice without paying to work with a human trainer. Of course, it has some wonkiness; I found the batteries altogether too hard to remove for charging (It’s not just me: It’s so confusing that there’s a special help page about it on the NURVV website), and I never got the system to work reliably with my Apple Watch, something it was supposed to be able to do. But those quibbles aside, I’d highly recommend this to other serious runners willing to invest in some great analytic gear. And at 30% off, you probably won’t find a better deal anytime soon.

This article was previously published. It’s been updated with new deal information.

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The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.