
The Buzzs! Buzzer is a special control specifically created for the Buzz series! . They are sold separately in fours or together with the set. They connect via USB on the PS2 versions. In the jump of the saga to PS3 , the buzzers became wireless, requiring a USB receiver.
The buzzers are made up of four colored buttons ( blue , orange , green and yellow ) to respond and a red button: the BUZZ! button. These are a replica of the buzzer of the TV contests.
Source Wikipedia