Side battery tray: A side battery tray lets you change the battery without removing the red dot, so you keep the zero. Models: C-more RTS3B V2.
Mounting
On a pistol with a factory optic cut, the red dot goes on an optic plate with the same footprint. On a pistol without optic cut, it goes on a red dot mount in place of the rear sight. See Optics ready plates and Red dot mounts.
Yes, if there is a plate or mount for your pistol with the same footprint as the red dot. Each red dot names its footprint in the table above and in its description.
Can I install the red dot myself?
Yes. Screw it onto the plate or mount with the screws that come with it. Put a drop of threadlocker on each screw and tighten it to the torque given by the maker.
Can I change the battery without removing the red dot?
Yes, on models with a side battery tray, for example the C-more RTS3B V2.