To activate your Electro Luminescent Zip Up Hoodie, press the button located on the battery housing (located on the inside of the jacket) for 3 light functions: Blink, slow flash, steady light. IMPORTANT NOTES: Item must be hand-washed and hang-dried. Remove the battery house before washing. Sizes are unisex, meaning a "Large" for a male may run a bit bigger for a female. LED Color: Blue Electro Luminescent Zip Up Hoodies are available in SM, MD, LG please see our other listing for addtional sizes. Comes ready to use with 2 replaceable AA Batteries.