A couple of years ago, I met a professional marathon runner at a friend’s holiday party, and immediately regretted every unhealthy decision I’d ever made in my entire life. Within a few minutes, my new acquaintance had informed me that he ran upwards of 150 miles a week; kept 10 pairs of running shoes on rotation at all times; and worked at the JackRabbit Sports store on the Upper West Side. He good-naturedly offered to give me a 15% discount if I was ever in need of some new running shoes, and, feeling guilty for having owned the same pair since high school, I decided to take him up on it.

Little did I know, JackRabbit Sports takes running very seriously — something I was in no way prepared for. It’s the type of store where they put you on a treadmill and record your feet; then play the video back in slow-motion and analyze how you run. I’ve worn many a pair of shoes until the soles were yapping, but it wasn’t until this excursion that I finally understood running shoes have lifespans — and mine were long dead. As my acquaintance informed me, it’s super important to replace your old sneakers to help avoid unnecessary injury; but how can you test if they’re still up to snuff?

Enter Mino: A gadget that tracks the grip and traction of your sneakers over time. All you have to do is slip the 2.55mm thick device under the sock insert of your running shoes, and it does the rest of the work for you. (It even comes with a spacer for the other shoe, so you’ll never feel any imbalance whatsoever.)

According to The Huffington Post, you should replace your running shoes every 300 to 500 miles; but when you don’t have a set running schedule, it can be tough to track your weekly (or, you know, yearly) mileage. Mino solves all that; and, after about 400 miles, alerts you that it’s time to go shoe shopping. Using a patented microchip, the device measures how many steps a person takes and the pressure with which they take them. That’s right: It can tell the difference between when you’re pounding the pavement and going for leisurely stroll — and takes everything into account.

To check the status of your sneakers, all you have to do is lift up the sock insert and press a button on your Mino. The gadget will then light up and tell you if your shoes are totally fine, on the verge of retirement, or ready to be replaced. At only $15 a pop, it’s a steal — especially compared to dealing with shin splints and sprained ankles.

Check out Mino in action below, and buy it for yourself right here.

(Images via Mino.)