Apple is working on self-tightening bands for the Apple Watch. Despite getting a patent, it hasn’t actually decided how it will work.

While putting on a watch isn’t exactly life’s most cumbersome task, an automatically tightening band would allow more precise fitting than using a buckle and holes. (That said, Apple did recently sell a hook-and-loop watch band for a mere $50.)

Apple has a particular interest in the idea however, with Apple Insider noting that imprecise fitting could reduce the accuracy of heart rate and accelerometer sensors. It also points out that the exercise that Apple Watch owners at least imagine they’ll start doing could loosen traditional straps during use.

The problem with the patent is that it seems very much an idea (which shouldn’t be patentable) rather than a specific solution. Apple outright says in the application that it’s looking at a range of possible ways to “dynamically adjust the fit of a wearable electronic device.”

The application doesn’t even settle on a general approach, with some suggestions involving the band lengthening or shortening, and others involving either the chassis or a section of the band extending outwards to press closely against the skin. Some of the approaches include using nickel titanium (which can change shape with temperature but revert to its original form) and using a ‘bladder’ filled with fluid or a gas.

There’s no word yet on whether or when Apple will turn the patented technology into a commercial product.