To activate, simply bend the stick until you hear it crack. This will release the chemical from within the glow stick and it will immediately start to GLOW! NOTE: Each pack contains 12 individually wrapped Red Glow Sticks with an included string necklace. Ordering ONE PIECE means you will only get ONE PIECE from the 12 pack. To receive a full 12 pack, you must order in groups of 12 pieces. Dimensions: Height: 6.0 in. , 15.24 cm. Width: 0.75 in. , 1.9 cm. String Necklace: Approx. 30.0 in. , 76.2 cm. Batteries are not required for this product.