Input Devices Supported : 6-button Controller
The standard Genesis controller only has 3 buttons. Unfortunately, the must-have game of the early 90's, Street Fighter 2, required 6 buttons. Thus, Sega released a redesigned six-button controller. It features X, Y, Z, and mode buttons in addition to the standard A, B, C, and start buttons.
6-button Controller is part of the Input Devices Supported category.