Once paired, a fitness machine shows the same workout stats on the Apple Watch and the gym display.

I gave it a try.

It also autopauses your Apple Watch if you pause a workout on the gym machine, too.

The gym machine reads your heart rate data and estimated calorie info, while the watch gets extra information from the gym machine, like stairs climbed or elevation.

Current GymKit partners include Technogym, Life Fitness, Matrix, Star Trac, Schwinn, Cybex and Stair Master.

Workout data gets synced to Apple Health (and your iPhone), too.

It basically means easy tap-in, tap-out for workouts.

GymKit is launching in one fitness center in New York to start, but Life Time Athletic and Equinox centers will start using GymKit-ready machines in North America in 2018, along with Fitness First in Australia.

Right now, GymKit is only being used on professional fitness machines in fitness centers. It's possible it might be used on home equipment in the future.

Existing fitness machines from existing GymKit partners can be upgraded to work with GymKit, but that's up to fitness centers.

It was easy to use, but it does require a tap on your watch to confirm the pairing.

If you forget to sync your watch when the workout starts, good news -- you could pair later on, and still sync all the data.

Shown here: a TechnoGym treadmill with GymKit ready.

There's an information panel, but you don't need it.

Tap to pair on a labeled panel is all that's needed.

Stair-climbers, ellipticals, treadmills and stationary bikes are the first types of machines that work with GymKit.

It seems like a road towards other fast-connecting accessories, too.