Unlike the Apple Watch or even most basic Fitbits, the Amazon Halo band doesn't have a screen. The app that goes along with it comes with the usual set of fitness tracking features along with two ideas.

You can use your camera to create 3D scans for body fat and the app will listen for the emotion in your voice to gauge how you feel about your lardieness. The Halo band will cost $99.99 and the service, which is required for Halo's more advanced features, costs $3.99 per month.

Amazon is launching it as an invite-only early access programme today with an introductory price of $64.99 that includes six months of the service for free. The Halo service is a separate product that isn't part of Amazon Prime.

The lack of a screen on the Halo band is the first indicator that Amazon is trying to carve out a niche for itself that's focused a little less on sports and exercise and a little more on lifestyle changes.

Alongside cardio, sleep, body fat, and voice tone tracking, a Halo subscription will offer a suite of "labs" developed by partners. They are short challenges designed to improve your health habits -- like meditation, improving your sleep habits, or starting up basic exercise routines.