user can select to wash the anus or vulva by pressing the corresponding button on the control panel. Usually the same nozzle is used for both operations, but at a different position of the nozzle head, and using different openings in the nozzle to squirt water at a different angle to aim for the correct spot. Occasionally, two nozzles are used, each dedicated for one area. The control logic is also attached to a pressure switch or a proximity sensor in the toilet seat, and operates only when the seat is occupied. The very first models did not include this automatic switch-off. The seat-heating feature is very common, found even on toilets that lack the bidet features. As most Japanese homes lack central heating – instead using space heating – the bathroom may be only a few degrees above freezing in the winter. Customization Most high-tech toilets allow water temperature and water pressure to be adjusted to match the preferences of the user. By default, the vulva receives less pressure than the anus. Researchers in Japan have found that most users prefer a water temperature slightly above body temperature, with considered optimal. The nozzle position can also often be manually adjusted forward or aft. High-end washlets allow selection of vibrating and pulsating jets of water, claimed by manufacturers to be beneficial for constipation and hemorrhoids. The most advanced washlets can mix the water jet with soap for an improved cleaning process. The washlet can replace toilet paper completely, but many users opt to use both wash and paper in combination—although use of paper may be omitted for cleaning of the vulva. Some wipe before washing, some wash before wiping, some wash only, and some wipe only—each according to their preference. Another frequent feature is a blow dryer, often adjustable between 40 °C (104 °F) and 60 °C, (140 °F) used to dry the washed areas. Advanced features Additional features may include a heated seat, which may be adjustable from 30 °C (86 °F) to 40 °C;(104 °F), an automatic lid equipped with a proximity sensor, which opens and closes based on the location of the user; and an air dryer and deodorizer. Some play music to relax the user's sphincter (some INAX toilets, for example, play the first few phrases of Op. 62 Nr. 6 Frühlingslied by Felix Mendelssohn). Other features are automatic flushing, automatic air deodorizing, and a germ-resistant