Below are 4 non-standard photo slides sizes (or types):
- 2.75 inch by 2.75 inch cardboard mount slide.
- 2 inch by 2 inch thick metal mount glass slides.
- 1.25 inch by 1.25 inch plastic mount slides.
- 2 inch by 2 inch cardboard mount with additional metal mount.
You can view different
2x2 photo slide film formats HERE.