The .450 No 2 Nitro Express, also known as the .450 Nitro Express 31⁄2-inch, was developed by Eley Brothers in 1903.

Eley Limited is a British manufacturer of firearms cartridges. Historically the company has produced a broad variety of ammunition, but today specialises in .22 Long Rifle cartridges for competitive target shooting. At the 2020 Tokyo Olympics, six of the twelve medals for cartridge rifle and pistol were won using Eley ammunition.