【Sister】

Despite its many functions,Sister one of the biggest questions about the Apple Watch from its critics — namely, what is it for? — may have finally been answered. Now it's a selfie camera viewer and video recorder on your wrist, when combined with the new CMRA camera band for Apple Watch.

Developed by former Apple Watch engineer Shawn Grening, the band features two cameras, a front-facing 8-megapixel camera and a self-facing 2-megapixel camera. Both cameras capture HD photos and video, which can be saved to the band's 8GB of embedded storage.

According to the company, the band's onboard storage allows for up to 30 minutes of video.

Along with band, the company has also created a unique charging dock that can charge the CMRA band and the Apple Watch simultaneously. That rechargeable charging dock has the ability to recharge both the Apple Watch and the CMRA band two times each.

Perhaps the most amazing thing about the well-designed device is the fact that Apple didn't think of it first. When the Apple Watch first launched, the first thing many analysts compared it to was the fictional smartwatch worn by Dick Tracy, a device that had its own embedded camera.

Fans of the Apple Watch have mostly expressed satisfaction with the device's existing functions, with most of the conversation revolving around longer battery life and a thinner form factor in future models. But the arrival of a dual-camera addition was probably more than any Apple Watch lover hoped for.

Of all the Apple rumors we've heard in recent months, a dual HD camera on the Apple Watch wasn't among them, so this product, which is touched by someone with a genuine Apple background, will likely be a welcome surprise.

So is this the accessory that will turn the Apple Watch from a relatively niche device (Apple still won't release unit sales numbers on the device) into a mainstream hit? Possibly. The selfie camera alone could be enough to boost Apple Watch sales.

Produced by Glide, the creator of the popular video messaging app of the same name, the CMRA will come in white, blue, gray and black and will sell for $149 to earlier buyers and $249 when becomes available via normal retail. Early buyers are expected to receive the device in spring of 2017.