Apple's new foldable "Duo" phone looks like a genuine new growth product, which is good news for Apple investors even though the stock is already expensive.

• The Duo folds open into a small tablet, stands up on its own, and can run video on one half while you draw or type on the other.
• A new T-Mobile handoff feature lets one phone number jump between two Apple devices, which could push people to own both a slim phone and a Duo.
• The bigger money angle is price: a Duo buyer spends around $2,000 instead of $1,200 on a Pro Max, lifting Apple's revenue per customer.
• The new Watch copies the health tracking that Whoop and Oura sell, landing right as Oura tries to go public.
• Apple stock is priced for under 10% growth ahead; if the Duo pushes real growth toward 20%, there's roughly 50% upside from here.

Outlook: Expect shortages at launch and analysts to raise their growth estimates, though the stock stays pricey until that faster growth actually shows up.