The .375 Flanged Magnum Nitro Express was introduced by Holland & Holland in 1912 as a rimmed version of the world famous .375 Belted Magnum for use in single shot and double rifles. It boasts similar ballistics to its belted counterpart but to slightly lower velocities. 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.