The ButtKicker Simulation Kit is for people who want a way to custom mount their ButtKicker - what most people tend to do is get a flat piece of metal and remove the seat. They place the metal panel on the seat rail frames and drill holes to match the mounting points for the seat, and then mount the ButtKicker to the center of the plate (Underneath), and then the seat mounted back to the frame, holding the plate down.
This will allow proper distribution of the forces of the system through the rear section of the cockpit.
The ButtKicker Gamer 2 is designed to mount direct to the Obutto cockpits by way of a clamping system designed by ButtKicker. The simkit is a more DIY version, and allows for multiple transducers to be used at once.