the drop module works thru the x-port 'channel' via electromagnetism...an elastic strap with a magnet on the end holds everything in place but only when the plane and tx are powered up...when you press the x-port button, it cuts power to the plane...this also breaks the circuit to the magnet and causes it to detach...whatever was contained within the strap falls...i put one on my pz cub...it's fun dropping stuff on unsuspecting seagulls....