This question applies to the legacy Photon camera models. The Photon product line and its accessories have been discontinued. The information here is provided for historical reference.
The legacy Photon 320 had a total of 7 attach points on the top and sides of the camera, designed for M3 screws. Because there were no attach points on the bottom, the tripod adapter was designed as an optional accessory to provide a ¼”x20 mounting interface to the bottom of the camera.
The legacy Photon 640 had 6 attach points: 2 each on the sides of the camera, and 2 on the bottom. All 6 screw holes were drilled for M3 helical inserts. The Photon 640 tripod adapter was available as an optional accessory to provide a ¼”x20 mounting interface to the bottom of the camera.