The Adjustable Hemmer
With its slide close the attachment will make hems up to 1 inch wide.
Loosen the screen at the front and move the slide until the pointer is against the desired width, then tighten the screw. Insert the edge of the material between the slide and the number gauge, and draw it backward and forward until the hem is formed, stopping with it's end under the needle. Lower the presser bar and sew, taking care in guiding the work to keep the hemmer full.
To make a gem more than one inch wide, loosen the screw, draw the slide to the right as far as it will go, and turn it towards you. Fold and crease down a gem of the desired width, pass the fold under the extension at the right of the hemmer, then insert the edge of the material into the folder and proceed to sew.