This smart pendant tells you exactly how long you can stay out before you get sunburn

We’re surrounded by gadgets that seem to want to help track everything about our fitness levels. Smartwatches track your steps, heart rate, blood oxygen levels, and can even take ECG readings. However, this new wearable wants to do something different: track your skin health and sun exposure.

That’s the main idea behind The90’s new pendant (via Notebookcheck). It’s called The Gem, and it looks like a normal pendant one might wear as jewelry. However, it has a sensor inside its titanium case that measures the amount of UVA and UVB radiation hitting your skin.

It comes with a companion app that shows your UV exposure in real time. It’s also highly customizable. Give it your skin type, habits, and other information, and the app will show you data personalized to your skin.

You can add information about your sunscreen, including the SPF value and the amount you’ve used, and the app will use that data to provide insights. It shows the time you’ve spent in the sun, including time spent unprotected, along with handy graphs of UVA and UVB exposure. It also has a burn timer that shows you an estimate of how long you can stay out before your skin starts suffering from sunburn.

According to the company, The Gem’s battery can last up to a week on a single charge, and it takes just about two hours to fully charge. It’s also splash-proof and has a fairly tiny footprint, about the diameter of a US nickel.

The Gem is available in two color options: gold and silver, and is available from The90’s website for $199. It’s worth noting that this is an introductory price that the company says will be available for four weeks only. Post that, the pendant will be available for $299.