The Cyclus Tools impactor guarantees an exact insertion of the Ahead claw into the steerer tube with a previously defined insertion depth.for Ahead claw 1" and 1 1/8". Turn the required bushing hand-tight (1" or 1 1/8") into the impactor. Now screw the claw to be mounted onto the grub screw using the cross hole as far as it will go. Place the tool on the steerer tube and knock it in as far as it will go with a hammer. Then remove the impactor from the steerer tube by turning the knurled screw to the left.