While Jawbone's Up3 fitness tracker is expected to go on sale next week after being delayed for months, there are two new wristbands that the San Francisco-based company wants to treat fitness fanatics with: the Up2 and the Up4.

The Up2 contains similar features as the Up3 and serves as a replacement for the Up24, but the Up4 is getting the most attention for allowing American Express customers to use the device to buy products will shopping, according to Mashable.

With the tap-to-pay feature, all users have to do is tap the screen of the wristband and they can pay for store purchases. Jawbone is the first fitness wearable company to include such a feature in its products, as this feature has been included in smartphones and smartwatches in the form of Apple Pay and Samsung Pay.

The Up4 comes with heart-rate monitoring, deep sleep analytics and other advanced health tracking features seen in the Up3, but it also includes an NFC chip in the strap so that users can make mobile payments, Engadget reported.

Tony Prentice, vice president of mobile payments at American Express, said the fitness tracker possesses this ability thanks to a long series of negotiations between Jawbone and AmEx.

The Up2, which has a design similar to that of the Up3, is 45 percent smaller than the Up24, 9 to 5 Mac reported. Users will be able to adjust the strap, and the wristband comes with vibrating notifications and the smart alarm clock found in most Jawbone wearables.

Fitness band lovers can get the Up2 now at Amazon, Best Buy and Jawbone's website for $100, but they will have to wait until later this summer to get their hands on the Up4, which will cost $200. Jawbone has yet to reveal if it will let VISA and MasterCard customers use its wearables to make mobile payments in the future.