Did you know that every Apple Watch has a hidden 6-pin diagnostic port behind its strap? It’s protected by a small metal door, but it’s incredibly easy to remove with just a sewing needle. The video below shows you how to get it open.

The short but helpful video was put together by the makers of the Reserve Strap, an upcoming Apple Watch strap that takes advantage of that diagnostic port and promises to deliver faster charging. The whole process takes just a few seconds.

https://youtu.be/DAbaX9XWvic

Just because the process is simple, though, it doesn’t mean you should try it. We don’t recommend exposing the diagnostic port if you don’t have to. It’s unlikely you’ll damage its pins, which appear to be very strong, but you could end up losing the protective cover for no reason.

It’s also worth noting that while the Reserve Strap plans to use this diagnostic port, Apple doesn’t encourage accessory makers to do this. It may do so in the future, but for now, the port is supposed to be for Apple’s use only; the company has actually designed a special strap that allows the device to charge while it’s on display in Apple Stores.

Don’t be too surprised, then, if a future Watch update disables the port unless it detects Apple’s own diagnostic tools. You should probably bear that in mind if you plan to buy accessories that use the port to add extra features and functionality.