Finally managed to hunt one of these down. They are out of production now, but basically just a wireless SNES controller. SNES is a great controller for retro and Indie games.
This is just the Sega Genesis version of the game controller. Just as good as the SN30 IMO.
A great stick for playing Shmups on the NES.
Fight Stick SG6
Same but for Genesis
Switch Pro Controller
The classic button layout of your standard twin stick controller, but with gryo controls and an endless battery life. Gyro controls are stupidly accurate for shooters, and gives you 3 points of movement allowing you to look to the left and shoot to the right simultaneously.
XB1 Wireless Controller
Also a great controller for modern games. Basically, just the Switch Pro, but no Gyros and less battery life.