Why is crop diversification important for Canada

This easel for photographic enlarging has retainers for holding paper in position on the easel, and improved means for adjusting the retainers for paper sheets of different size. There are clamps for holding the retainers in set positions and provision for preventing parts of the clamps from becoming disconnected when turned in directions to release them. A single clamping screw for each retainer expedites adjustment. Masks for paper of different size have the same spacing of screw-receiving openings corresponding to a single standardized spacing of threaded openings in the easel plate.