Septa Sync

Septa Sync is a separate paid playlist inside the app, priced at $39 as a one-time purchase.

It is a set of seven frequencies designed to induce a waking sleep state, and it is currently the subject of a research study with MIT. High Frequency Highway is the only app licensed to sell it.

It sits highlighted on the home screen. The purchase is separate from a premium subscription, and once you buy it, it stays in your account.

If you have already paid and it is not showing, use Restore Purchase in Settings.