On our #4, #4 1/2, #5 1/4W and #6 bench planes, the frog extends all the way to the sole. This unique design provides complete blade support, reducing chatter, and allows quick mouth adjustment. It can be closed to a narrow slit for fine shavings and minimum tear-out, or opened for heavier cuts, all without removing the lever cap or other parts; just loosen two screws and set the opening with the thumb wheel. Norris-type adjuster for easy and accurate blade setting. Blades are 1/8" thick.