Still not sold on this whole smartwatch concept? Maybe you have a regular “dumb” watch that you still wear for sentimental reasons, or maybe you just don’t want your private text messages flashing on your wrist for the world to see. Now there’s a way to make any watch smart and still keep your notifications private with Chronos.

Chronos is a thin metal disc that sticks to the back of your watch. At just 2.5mm, it’s only really noticeable up close. It combines customizable notifications with fitness tracking, fits on 80 percent of watches sold today and starts at just $99.

The device has two main ways of getting your attention: vibrations and lights. You can set different patterns and colors to represent specific pre-selected apps and people. So if your watch flashes a purple light, it might mean your Uber has arrived, while a yellow pulse could mean your mom is calling.

You can also respond with two different inputs: tapping on the top or side of the device. That makes it possible to dismiss notifications and even control the music on your phone.

Fitness tracking on Chronos is pretty straightforward. The company’s own app, which is already running on iOS and heading for Android, organizes all your data in one clean graphic. You can also feed that information into another heath tracking app if you prefer.

Chronos is water-resistant and packs a 36-hour battery. You’ll probably want to charge it overnight, and the company’s designed a beautiful wireless dock that will look good on any bedside table.

Chronos is launching for just $99 in pre-sale. Once it actually hits the market the price will go up a bit to $129.