9.75"Lx 7.5"W x 3.5"H, One size fits most, elastic band can let you feel confortable when you wear this mask<br>4 different modes: off, constant on, slow flicker, fast flicker, uniform and soft light will not make eyes produce tension, fatigue<br>You can wear this mask on Masquerade parties, halloween, Rave Party, parties, discos, clubs, birthday parties, festivals and events, this mask is also a great gift for birthday<br>This mask use 2* AA batteries (not include), low power consumption, more than 24 hours long life, clip the power pack to your pocket or onto your clothing<br>Please note: It will make a slight high pitched tone when the mask turn on. But please don't worry. This is normal. To aovid the slight high pitched tone, we suggest our customer place the battery pack in your pants and shorts pocket