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 LEDs Our Happy Birthday light-up pendant is sold by the piece. Please order in increments of 1 piece.