$100 · Lumo Lift

This Lumo Lift is new-in-box, has not been used. Specs from the website: compatible with iOS 10 and newer/Android 5.0 or newer; charges in 2-4 hours, charge lasts 1-2 days; device weighs 11.5 grams with dimensions 1.75" x 1" x 1/2" for the sensor; the magnetic clasp is 0.6" x 0.6" x 0.1" and weighs 1 gram. Besides vibrational posture correction it also keeps track of steps/distance/calories, records your history, and can be linked to other devices via Bluetooth. Two photos here are of the package of my device, three were lifted from the website, and one shows the going price on Amazon.