The G25 load sensor modification is designed to replace the potentiometer and spring mechanism in the Logitech pedal assembly. When used in the brake position, it allows a more realistic action of braking by offering mechanical resistance similar to the amount found on a real car.
The stock G25 pedal assembly uses a potentiometer to measure the amount of braking the user inputs. This means that the pedal must travel a certain distance with little mechanical resistance to a point the user feels proper maximum braking is achieved. This method is unrealistic and difficult to do with repeated accuracy.
The modification offered here uses a special load sensor integrated with a mechanical actuator that is specially designed to fit into the assembly without any further difficult modification by the user.