This slim sensor clips on to snug-fitting clothing to monitor posture and alert users if they slouch. Secured below the collarbone with an unobtrusive magnet, the electronic trainer is user-calibrated to identify each user’s ideal posture. If it detects slumping, the device gently vibrates to coach the wearer to sit or stand up straighter. Paired via Bluetooth to a smartphone running a free app, the trainer tallies hours of good posture, lets users set goals, and stores up to a month of data to track progress. It also doubles as an activity tracker to calculate steps taken, distance travelled, and calories burned. The lithium-ion battery lasts up to five days after a two-hour charge with the included USB dock. Compatible with select Android devices or Apple devices running iOS 7.0 and later. 1 3/4" H x 1" W x 1/2" D. (1/2 oz.)