CNBC is reporting that Apple has unveiled a new gym initiative called “Apple Watch Connected.”

At the time of launch, four gyms have joined the program, including Basecamp Fitness, Orange Theory, YMCA and Crunch Fitness, although that number will likely grow quickly since its free for gyms to participate. Participating gyms must offer four tiers to qualify:

• The gym has to provide iOS and Apple Watch apps for members to login at the gym, see classes and track their fitness.
• The gym has to provide a way for Apple Watch owners to earn some kind of credit or reward, such as a way to earn money off of their bill if they work out a certain amount.
• The gym must accept Apple Pay.
• With few exceptions, gyms must support GymKit on cardio machines. This allows the machines to provide a wealth of information to Apple Watch, more than it might be able to get on its own, about the type and intensity of a workout.

As CNBC points out, there’s a big benefit to gyms, as Apple Watch integration will likely lead to lower membership turnover.