Abstract: The present invention includes a coupler assembly for attaching a work implement to a work machine. The coupler assembly includes an attachment hook which has an upper jaw with an adjustment surface and a lower jaw with a locating surface. The adjustment surface of the upper jaw includes a plurality of interconnected arcuate notches therealong so that a pin receiving opening is defined between the adjustment surface and the locating surface. The plurality of arcuate notches in the adjustment surface in cooperation with the locating surface allow for a plurality of various pins to be aligned and seated automatically within a seating position correspondent to the diameter of the pin. The automatic alignment and seating virtually eliminates operator involvement during the alignment process, thereby reducing time and costs.