I'd encourage you to pay slightly more for the 2600 Daptor D9 instead. It connects almost every retro controller imaginable. Here's a list:
Atari 2600 Joystick
Atari 2600 Driving
Atari 2600 Paddles (both paddles)
Atari 2600 Keypads
Atari 2800/Sears Video Arcade II
Atari 7800 Pro-line/CX78 gamepad
Atari CX22 & CX80 Trak-balls, native mode
Atari CX85 Numeric Keypad
Atari Flashback 1 (AtGames)
Atari ST mouse
Amiga mouse
Amiga CD32
Bally Astrocade
CBS Booster Grip
ColecoVision original, SA including spinner, Driving
ColecoVision Flashback (AtGames)
Commodore Paddles (both paddles)
Fairchild Channel F
Famiclone (NES, SNES, Famicom with adapter cables)
FM Towns Marty
Gemini Dual Command
Intellivision original (INTV-1 dongle available)
Intellivision Flashback (AtGames)
Magnavox Odyssey 2
MSX, x68000
Sega Genesis: 3 & 6 button d-pad & arcade stick
Sega Master System: d-pad, Sports Pad, Paddle HPD-200
3DO
TI-99/4A (both joysticks)
The comparison between Daptor models is available here: http://www.2600-daptor.com/index.htm