These holders fit The 76 Camera Variation 2 (Wet-Plate Type), The 76 Camera Variation 3 (Scovill Type), a rare type of 76 Camera, and the American Optical Waterbury-Type Variation 1, a rare Waterbury-Type camera that is larger than its more common Waterbury brethren. Despite the fact that the size of the holders is exactly the same as the camera backs of these two cameras, neither of these cameras has its holder peg locations exactly the same as the holders just mentioned, demonstrating that, in this era, not all the parts on these cameras are not interchangeable. It would take Henry Ford to pioneer that concept.
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