The DYI crib mobile arm allows you to create your own signature nursery mobile. Mobile arm is complete with mobile arm, bolt and cap attachment mechanism, rotating 4 prong canopy hooks, wind-up music box that plays Brahm's Lullaby, fabric cover for mobile arm in your choice of colors and instructions for assembly. Crib mobile is constructed from heavy duty plastic and is very sturdy and secure. Simply add your own mobile characters to the rotating canopy hooks.