Box to store your guitar picks.1.- Select a spring high enough and not too strong that allow rising the platform (red part) to the top (blue part). 2.- Place the spring into the box (green part) housing. 3.- Apply glue on the box (green part). 4.- Set the platform (red part) over the spring and keep it down with a pencil. 5.- Put the lid (blue part) on the box (green part) and press until sticking. Sorry for the translation (google traductor) ;)