To activate your Light Up Hard Shell Bow Headband, remove the pull tab & slide the switch on battery pack. Lights shine a calm steady light; no flash. One size fits most. NOTE: Though generally a product for the young, adults can wear these LED Bows too - just take the time to stretch out the pliable black plastic. Headbands run small fresh out of package. Dimensions: Bow Height: 8.5 in. Bow Width: 6.25 in. LED Colors: Blue Comes ready to use with 3 replaceable AG13 Batteries.