The Undetectable Extention Charm

An advanced spell that was heavily controlled, the Undetectable Extension Charm was used to expand the interior space of an object without changing the external dimensions. The charm could be used on practical objects such as family tents and official cars. Newt Scamander famously used the charm on his magical briefcase in order to house a magical menagerie, whilst Hermione Granger displayed her talent for complex magic when she cast this charm on a small beaded handbag in order to carry all the essentials, including a mobile library, that she, Harry and Ron would need while on the run, looking for Horcruxes.