Head phones - there are two headphones (in the photo they are seperated by rooom).
The button to press can be located anywhere (can take three players to play or forced 2 player)
When the button is pushed a sound comes (amount of rings, beeps,etc) and headphones 1 hears 2  sets of codes and headphones 2 hears another 2 sets of codes to make a 4 digit numeric code. 
It is in the clueing on what headphone is first  (left or right) 
Mirco SD card for sounds.
 
Head phones come white with leather inside to wipe clean after every game play. 
 
Sound file extra ready to play $50.00 canadian
or you make your own - no sound file provided (micro SD card insert)
 
For extra $25 Canadian you can add a second button so you can have two buttons - each for 1 head phone and needs to be held down to hear sound.