EZ Wiring advertises that the kit offers easy adjustment of the arc the wiper will travel in. Removing the rear cover of the motor reveals this drive wheel with holes drilled at various distances from the center. By switching the arm to a different hole, you can adjust the arc. The end of each piece of aluminum tubing needs to be flared in order for it to locate in the motor housing and gearboxes. The flare locates in this slot in the housing.