Design elements, form factors, and construction can also vary significantly between models depending on the intended use. Examples of specialized models of laptops include 2-in-1 laptops, with keyboards that either be detached or pivoted out of view from the display (often marketed having a "laptop mode"); rugged laptops, for use in construction or military applications; and low-production-cost laptops such as those from the One Laptop per Child (OLPC) organization, which incorporate features like solar charging and semi-flexible components not found on most laptop computers. Portable computers, which later developed into modern laptops, were originally considered to be a small niche market,