The ellie bunk bed is a unique modern twist on the traditional childrens bunk bed design with the option to add the ellie trundle bed storage drawerto instantly change the bunk bed from a double into a triple bed for whenever you may need it alternatively you can use the optional trundle as a storage drawer by not adding a mattress inside please see the bundle deal for mattress options we strongly recommend that the cabin bed mattress is purchased for the top bunk as it has a depth of 15