a warning tone at a predefined altitude. Contemporary audibles have evolved significantly from their crude beginnings, and sport a vast array of functions, such as multiple tones at different altitudes, multiple saved profiles that can be switched quickly, electronic logbook with data transfer to a PC for later analysis, distinct free fall and canopy modes with different warning altitudes, swoop approach guiding tones, etc. Audibles are strictly auxiliary devices, and do not replace, but complement a visual altimeter which remains the primary tool for maintaining altitude awareness. The advent of modern skydiving disciplines such as freeflying, in which the ground might not be in one's field of view for long periods of time, has made the use of audibles nearly universal, and virtually all skydiving helmets come with one or more built-in ports in which an audible might be placed. Audibles are not recommended and often banned from use by student skydivers, who need to build up a proper altitude awareness regime for themselves. Auxiliary visual altimeters. These do not show the precise altitude, but rather help maintain a general indicator in one's peripheral vision. They might either operate in tandem with an audible equipped with an appropriate port, in which case they emit warning flashes complementing the audible tones, or be standalone and use another display mode, such as showing either green or red light depending on the altitude. Speaking altimeters (also known as voice altimeters). Another type of altimeter that combines both audible and visual altimeter functions. Unit has all necessary altitudes used in Skydiving and announces it as a number in Skydiver's native language. These are also inserted into helmet (the same pocket size as for audibles), but emit voice with automatic volume adjustment depend on the speed to clear hearing. Speaking altimeters usually has software configuration via mobile application. Main goal of this type of altimeter is strong security feature for experienced skydivers, so they always know own current position that very useful for FS load organizers or AFF instructors as well. The exact choice of altimeters depends heavily on the individual skydiver's preferences, experience level, primary disciplines, as well as the type of the jump. On one end of the spectrum, a low-altitude demonstration jump with water landing and no free fall might waive the mandated use of altimeters and use none at all. In contrast, a jumper doing freeflying jumps and flying a high