Modern leisure narrowboats are used for holidays, weekend breaks, touring, as permanent or part-time residences. Usually, they have steel hulls and a steel superstructure, but when they were first being developed for leisure use in the 1970s glass reinforced plastic (fibre-glass) or timber was often used above gunwale height. Newer narrowboats, say post 1990, are usually powered by modern diesel engines and may be fitted inside to a high standard. There will be at least internal headroom and often or usually similar domestic facilities as land homes: central heating, flush toilets, shower or even bath, four-ring hobs, oven, grill, microwave oven, and refrigerator; some may have satellite television and mobile broadband, using 4G technology. Externally, their resemblance to traditional boats can vary from a faithful imitation (false "rivets", and copies of traditional paintwork) through "interpretation" (clean lines and simplified paintwork) through to a free-style approach which does not try to pretend in any way that this is a traditional boat.