The Sega Genesis Flashback HD is smaller than an actual Genesis, but it’s also bigger than two SNES Classics put together. This is understandable, though, because of the actual functioning cartridge slot, which limits how small this thing could really be while still maintaining the classic Genesis proportions. It has an AC adapter (not USB) and HDMI out.The unit includes two wireless controllers that each require two AAA batteries (not included). The design of these is based on, if not entirely 1:1 accurate to, the six-button Genesis controller that Sega rolled out around the same time that Street Fighter II came to its hardware. They feel a little light and hollow, but they work fine. A switch on the top of each controller lets you set them to control Player 1 or Player 2.