Flare tip cannula for EDS Systems. The triggering of the system depends on the EDS unit sensing the drop in pressure during the initial part of each inhalation. This is sensed internally by a pressure sensor, which then triggers a valve and delivers a pulse of Oxygen. In most cases, the standard tip cannula will accommodate this requirement. However, if the user is experiencing trouble triggering the EDS unit or has larger than average size nostrils, then the flare-tip cannula should be used.