The Edelbrock dipsticks are designed for use with the Edelbrock Performer Series and Thunder Series AVS carburetors only and not with other brands. These dispensing rods allow you to refine your carburetor for optimal performance and are used to control the air/fuel mix. Since dispensing rods are available with different step combinations, it is possible to independently change the air/fuel ratio for both cruise and power modes with a single rod change. The small area at the tip of the rod is the power step and the thicker area next to it is the cruise step with a dimension of 0. 073 x 0. 052 These rods can be changed in seconds by removing the single hold-down screw and are sold as a pair.