WDCS El Sound Activated Novelty Party Toy Neckties For Rave EDM Clubbing and Halloween Party A Perfect Party Apparel for Music Festival, Rave, EDM, and Costume Parties. One Size Fits All With Adjustable Neck Strap. Adjustable Sensitivity To Music Volume. The Best Blinking Flashing Party Accressories and Rave Gear You Can Find. Takes Two AAA Batteries (NOT INCLUDED) 30 days hassle-free return or exchange. WDCS is a trademark which belongs to Wantedcases, Inc.