7.63x25mm Copper FMJ Mauser inert ammunition for the Mauser C96 automatic service pistol. The 7.63x25mm Mauser cartridge was the highest velocity commercially manufactured pistol cartridge in existence until the advent of the .357 Magnum cartridge in 1935!
Cases are brass, bullets copper FMJ. Now a very hard to get round since there is no legal pistol shooting in the UK, hence the price, free from explosive, no licence required.