carelessly. In addition, a user must be reasonably mobile and flexible to use a hand-held bidet shower. Conventional or standalone bidet A bidet is a plumbing fixture that is installed as a separate unit in the bathroom besides toilet, shower and sink, which users have to straddle. Some bidets resemble a large hand basin, with taps and a stopper so they can be filled up; other designs have a nozzle that squirts a jet of water to aid in cleansing. Add-on bidets There are bidets that are attachable to toilet bowls, saving space and obviating additional plumbing. A bidet may be a movable or fixed nozzle, either attached to an existing toilet on the back or side toilet rim, or replacing the toilet seat. In these cases, its use is restricted to cleaning the anus and genitals. Some bidets of this type produce a vertical water jet and others a more-or-less oblique one. Other bidets have one nozzle on the side rim aimed at both anal and genital areas, and other designs have two nozzles on the back rim. The shorter one, called the "family nozzle", is used for washing the area around the anus, and the longer one ("bidet nozzle") is designed for washing the vulva. Such attachable bidets (also called "combined toilets", "bidet attachments", or "add-on bidets") are controlled either mechanically, by turning a valve, or electronically. Electronic bidets are controlled with waterproof electrical switches rather than a manual valve. There are models that have a heating element which blows warm air to dry the user after washing, that offer heated seats, wireless remote controls, illumination through built in night lights, or built in deodorizers and activated carbon filters to remove odours. Further refinements include adjustable water pressure, temperature compensation, and directional spray control. Where bathroom appearance is of concern, under-the-seat mounting types have become more popular. An add-on bidet typically connects to the existing water supply of a toilet via the addition of a threaded tee pipe adapter, and requires no soldering or other plumbing work. Electronic add-on bidets also require a GFCI protected grounded electrical outlet. Usage and health Personal hygiene is improved and maintained more accurately and easily with the use of both toilet paper and a bidet as compared to the use of toilet paper alone. In some add-on bidets with vertical jets, little water is used and toilet paper may not be necessary.