Virtually undetectable they come in many sizes ex.-4'x6'x4' - 12'x16'x10' with 4'x4'access hatches that can be made to blend with the surrounding area ex. landscape,tile,concrete,hardwood,etc.Usually used for hiding large equipment,they can be used for Personal Protection,Storage of Valuables and even All Climate Gardening/Growing.Endless electrical panel,lighting,HVAC and water connection options.You can even construct shelters and utility buildings over them.Installation Available.Please contact us for further information.