These are small flashing lights that are motion activated. Any small vibration will cause them to flash. They are about 3/4" wide, 7/8" tall, and 1/4" thick.
They are battery operated, but the batteries are NOT replaceable. Typical flashing life is 6-12 months. They are waterproof, so in addition to using in wands, bows, bracelets, they can also be used in clothing!
They are available in singles or lots of 25.