The Buzz! Buzzer is a special controller set designed specifically for the Buzz! game series. The controller features four handsets, each of which has a large red buzzer button and four smaller coloured buttons for picking the answer from the on-screen options. The buzzer set is a USB device, and connects to the USB ports on the PlayStation 2 and PlayStation 3.
The Buzz Junior games came with a new set of Buzzers but like the PS3 games the old Buzzers can be used. These new buzzers still use wires and are not wireless. The only difference is that the buttons, are shaded that colour , instead of the outline.
Buzz!: Quiz TV saw the release of a wireless version of the buzzers. They connect to the PS2 or PS3 system via a USB dongle. Each dongle can support up to 4 wireless buzzers so this means another dongle is required for 8 player play with 8 wireless buzzers. The wireless buzzers can be used with both the PlayStation 2 and PlayStation 3 and all previous Buzz! games.
Source: Wikipedia, "Buzz!", available under the CC-BY-SA License.