Early Access registration for the Amazon Halo is now open, but you may be wondering what this means and why you can't order the new fitness tracker with Prime membership and 2-day delivery.

Unlike the best fitness trackers now available from the online shopping giant, the Amazon Halo is not for sale. Normally $99.99, it is on sale for $64.99 as of this writing, but you simply cannot add it to your cart. Instead, Amazon Halo's landing page prompts you to register for Early Access.

Like Amazon's Day One program, which is used to send quirky products like the Amazon Echo Frames and Amazon Echo Loop to select testers, Early Access is a registration-based system for securing new devices from the company. It is, however, more inclusive than Day One.

If you are interested in trying out Amazon Halo, you will need to fill out a short survey while signed in to your Amazon account. Once completed, Amazon may send you an email invitation to execute your Halo order.

With a little patience, you may be able to get a new type of fitness tracker and health service that can analyze your body fat, sleep, and physical condition.

Here's how to sign up for early access to Amazon Halo.

1. go to the Amazon Halo product page and sign in to your Amazon account if you are not already logged in.

2. select your desired Amazon Halo band color and size, available in 3 colors (black, pink, gray) and 3 sizes (small, medium, large).

3. Click the yellow button marked "Request Early Access" to be redirected to the request form.

4. fill out the Amazon Halo Early Access Survey. Fill out the survey as best you can, and when you are done, click "Complete Request."

If you successfully registered for Amazon Halo Early Access, you should see this when you return to the Amazon Halo product page:

Now, sit back and wait. Keep an eye on your inbox connected to your Amazon account, as Early Access invitations will be sent out one by one.