The travel trailer is the #1 selling RV type. Sizes range from about 9' up to around 40'. They are relatively low in cost and can be towed by many vehicle types-- smaller travel trailers can be towed by SUV, the ultra-lights can be pulled by a 1/2 ton pickup and the larger trailers can be towed by 2500/3500 series trucks. Most models 17' and larger are fully self-contained, with a full bath, kitchen, and bedroom. Options include: slide-outs, one door, two doors, bunk beds, cooking facilities, a refrigerator, heating, air conditioning, toilet, shower, water tanks (fresh water, grey water, black water), faucets, sinks, a LP (propane) gas supply, and a separate 120v electrical system.