This is a clip-on, white-designed item that helps with sleep management. I bought it because I wanted to measure the in-bed climate. I'm selling it now because I haven't been using it lately. It seems to be a compatibility issue with the smartphone and app. While it didn't collect data properly with my main smartphone (OPPO Reno9A), it worked fine with my sub-smartphone (AQUOS wish3). Batteries are not included. A button battery (CR2032) is required. To open the device (after removing it from the cover), place it with the "BRAIN SLEEP" logo facing your left palm, and then apply gentle pressure with your right palm while rotating your right hand counterclockwise. If your hands are slippery, moistening them slightly will make it easier to open. - Brand: BRAIN SLEEP - Color: White - Shape: Round - Design: Clip-on