4 Stereo Slide Mounts: A cool new look! We hadn’t seen these fun stereo slide mounts before, so we knew we just had to have them! Each heavyweight paper slide mount is 3 1/4”x4” and has four 1”x3/4” windows. Use it as one large piece or separate them into thirds. Ink them, chalk them or cover them with patterned paper for a personalized look.