What is catridge fuse?

A cartridge fuse has a cylindrically shaped body (usually glass or ceramic) and has metal endcaps (or 'ferrules' in U.S.) which are designed to engage electrically with a fuse holder. They are designed to be easily replaced by the user without the need for tools. They tend to be used for smaller current ratings (i.e. less than say 100A). Higher current rating fuses tend to have bolted connections to prevent overheating of the connection.