Light up your party and light up your guests with our Happy Birthday Hat light up necklace. Each Happy Birthday Hat round pendant is 1 1/4" in diameter and comes on a 24" cord. All pendants have a multi functional switch, slow blink, fast blink or constant on and come with batteries included and installed and white L.E.D's. Our Happy Birthday light up pendant is sold by the piece. Please order in increments of 1 piece.