To activate press the black button located on the back of the necklace. Set the Light Up Red Paw Print Charm Necklace to a fast flash, a slower blink or still light. Height: 3.18 in. - Width: 3.12 in. - Depth: 1.25 in. Necklace Length: 36 in. LED Color: Red - Batteries: Includes 3 replaceable AG13 batteries. - Weight: 0.24 LB