Trundle beds are usually considered a pair of beds, one a twin bed, and the other slightly smaller on rollers or casters so that it may be put beneath the upper twin bed for storage. Trundle beds are a space-saving idea and allow for an extra separate bed to be available when necessary, but do not require the second space constantly. The lower bed on some trundles can "pop-up" to be the same height as the twin it is stored beneath, creating a regular-height bed. Often used as daybed

Daybed

Daybeds are used as beds as well as seating. They can be made out of wood, metal or a combination of wood and metal.A cross between chaise longue, couch and a bed....

s, trundle beds are less common than bunkbeds for children. Due to storing one bed beneath the other, neither bed usually has a box-spring

Box-spring

A box-spring is a type of bed base typically consisting of a sturdy wooden frame covered in cloth, and containing springs. Usually the box-spring is placed on top of a wooden or metal bedframe which sits on the floor and acts as a brace. The box-spring is usually the same size as the much softer...

. When not used for sleeping, the lower bed, with mattress removed, may be used as a general storage drawer.