Abstract: An adjustment wedge having means for verticallay adjusting the wedge in a double clip member of an optical lettering guide provides adjustment of the angular relationship between a tinted transparent window card held in one clip of the guide and an image-producing card held in the other clip. The adjustment wedge is used to precisely adjust the angle between the window card and the image-producing card to match the angle between the window card and the drawing surface. Following such adjustment, the card image appears to be superimposed exactly on the plane of the drawing surface.