Not familiar with that vendor, but the encoder looks like a 2-player Xin-Mo. (gamepad-style encoder)
I believe that GGG and Paradise Arcade carry similar boards with prefab wiring harnesses.
GGG and Paradise get theirs from reputable sources, but I'm pretty sure there are some low-quality knockoffs out there that caused some people to complain about lag.

You may want to stick to known good vendors instead of looking for a 1-click package deal.

Scott