Both the straps for the 38mm and 42mm Watch will increase the battery life to "48 hours of functionality." The product adheres to Apple's Band Design Guidelines and does not violate your AppleCare warranty.

Though allowing a third party intrusion by the tech giants is a big change, for extending the battery life of a device so drastically, the cost upwards of 10,000 dollars may be worth the premium for some users.

However, nearly 20 percent of Apple Watch buyers are not only shelling out hundreds of dollars for the timepiece but are springing for a spare band too, giving the tech giant a profitable second dip into customers' wallets.

The data from Slice Intelligence, a research firm that mines e-mail receipts, offers a rare window into the money-making potential of Apple's first brand-new product under CEO Tim Cook.
               
The ever-secretive company has yet to release how many units of the watch it has sold, let alone how profitable it is. Slice estimates the company has sold 2.79 million as of mid-June.
               
But if the band purchases are any indication, sales of the watch itself are just the beginning of Apple's profits.
               
Although the entry-level sports band retails for $49, it costs only about $2.05 to make, according to an analysis of the 38-millimeter size by IHS, a technology research firm.
               
The estimates do not include expenses such as packaging and shipping and may not capture the full cost of the material Apple uses to make the band, said analyst Kevin Keller of IHS.