Cylinders typically hold six cartridges—which is why revolvers are sometimes called "six shooters". But some small frame revolvers only hold five cartridges, due to the smaller overall size of the gun. Several models of .22 rimfire caliber revolvers have cylinders holding nine or ten rounds. As a general rule, cylinders are not designed to be removed from the firearm except for cleaning. A speedloader or moon clip can be used with some revolvers for rapid reloading.