Cross bar for stretcher bar K45

Crossbar with matching recess for stabilising larger formats created with the K45 stretcher frames. Depending on the frame size and tension, unattractive bending can occur in stretcher frames covered with canvas. The crossbar, inserted before applying the canvas, prevents this. For formats over 70 cm, two crossbars may be advantageous. The crossbar is not suitable for building the actual frame itself.