To activate, twist backing clockwise. To deactivate twist counterclockwise.- Piece attaches magnetically. - To attach, remove magnet on back of the piece. Hold magnet behind shirt (or desired location) and attach piece on opposite side. Height: 2.25in. , 5.7cm. Width: .75in. , 1.9cm. LED Colors: Yellow, Red, Blue. Batteries: Includes 2 replaceable CR927 batteries.