Starts by pressing metal top. Plays 25-55 seconds depending on tune. Replaceable battery lasts for 1000's of plays. Glue in or flush mount installation. Pom-poms and other items can be glued on top to cover it. Use sound cup when sewing it into stuffed animals. 1 3/8" diameter, 1/2" thick. Takes 1 LR1130 battery.