Next up from Fitbit: Tech that will help you hit your fitness goals without ruining your style.

The activity tracking giant gave fashionistas some love in 2016 with the introduction of the Alta, a sleek fitness tracker with sharper style than its other, clunkier offerings. Collaborations with fashion designers like Tory Burch and PUBLIC SCHOOL followed, giving the Alta an extra aesthetic boost and its wearers more options to accessorize their device.

Fitbit's next step for the line, the Alta HR, keeps that aesthetic focus but amps up its tracking power. The company's engineers shrunk its PurePulse heart monitoring tech down to a chip small enough to fit in the Alta's housing, creating what Fitbit claims is the world's slimmest wrist-based activity tracker with that capability.

The device was unveiled at an appropriately sweaty spin class event hosted by brand ambassador Julianne Hough in New York City.

The Alta HR is 25 percent skinnier than the next smallest Fitbit with PurePulse, the Charge 2, which can be overly chunky for people with smaller wrists. That's a welcome improvement for the Alta's target audience -- the company has unabashedly marketed the device to women.

The Alta HR looks the same as the original Alta on the outside, so there's not much change aside from the heart monitoring capabilities. Fitbit claims battery life has improved enough for users to go a full week between charges, but we'll judge that when the time comes for a full review.

Fitbit also announced some new sleep tracking features it has on the horizon: Sleep Stages and Sleep Insights, which were developed using data from the 3 billion nights of sleep (2.5 million years!) logged by Fitbit wearers since 2012, look to help users hack and track their rest.

Sleep Stages, which will be available for Fitbit devices with PurePulse (Charge 2, Blaze and, of course, Alta HR), estimates the time spent every night in the three stages of sleep: light, deep and REM.

Sleep Insights is less tech-dependent, so it'll work for all Fitbits that track sleep, giving wearers more focused advice on how best to tailor their day-to-day activities for better snoozing.

The Alta HR is now available for preorder for $149.95, with a wider release in stores in April. That's $20 more than the original model, but the addition of the heart rate monitoring tech might justify the boost for those looking for a sleeker way to track their BPM.

Sleep Stages and Sleep Insights will roll out later via an update to the Fitbit app sometime this spring.