In a real car the amount of brake applied varies based on how hard you press, not by how far the pedal travels. A load cell is an electronics device which replaces the potentiometer in your controller. It translates pressure instead of rotation to the game, which produces a more realistic feel, and gives you greater control over the lock-up point of your brakes.
This kit allows you to modify your standard TSW, TSW2, or TSW Evolution Pedal set to use a load cell. This is only an option for true USB controllers: either those that had integrated USB when new, or have been upgraded to USB at some point (external USB electronics are fine). This kit is not compatible with the Rockfire USB adapter or gameport.
The kit includes a new wood base which is specially modified to fit the load cell components. Installation requires that you remove your metal frame from it's current wood base, remove the old brake potentiometer, spring, and pedal linkage, then mount the frame to the new base, attaching the new compression spring linkage to your brake. The kit supports both standard and spread-pedal controllers.
There is a considerable amount of adjustability to this pedal configuration. It's possible to calibrate it so that it works almost identically to a potentiometer, or to make it work very much like a real race-car, requiring a large amount of force. It's possible to alternate this depending on the type of racing you're doing (competative road-racing vs. superspeedway ovals, etc..)
In addition, having larger pedal pads can make the pedal more comfortable, so consider getting a set of GT pads if you don't already have them.
With a regular brake, you don't have to worry about how stable your pedals are mounted, how sturdy your chair is, etc.. But with this type of pedal, you will find that a regular office chair with wheels just won't stay put, and you will need to make sure your pedals don't move away from you. We address this need by incorporating an anti-tip bracket into the kit which is fastened to the back of the pedals. On carpet this alone will keep the pedals solidly in place, but on a smooth floor, you will likely need to put something between this bracket and the wall to keep them from sliding away under heavy pressure. Some sim racers have cockpits in which everything can be bolted solidly, so if you don't need this bracket, you can order the kit without it.
Because the load cell is an analog device, it doesn't work directly with the original version 1.0 TSW Evolution Digital, so if you have one of these, you will need to purchase the internal circuit board as well, which has its own USB connection, independent of your wheel. In October '08, the digital 2.0 circuit board became standard in digital controllers which does accomodate an analog axis, negating the need for the additional circuit board in models with this board (check in the windows device manager to see if yours is the 2.0 version).
Being an analog device however, doesn't mean the load cell is subject to wear like a potentiometer. This type of device is like an optical encoder in that it is expected to last indefinitely.