The Rock must be mounted at 5’ (five feet) from the floor.
When the Rock is mounted at 5’, the Rock can authenticate faces between 43” and 88” from the floor. (this dimension refers to the height of one's eyes from the floor)
Note that when a very tall person or someone in a wheelchair is situated very close to the Rock - e.g. less than 1’ away from the Rock - their face may no longer be within the field of view. The Rock is intended to authenticate people as they approach. If a very tall person, or a person in a wheelchair failed to authenticate it may be necessary to back-up a couple of feet and re-approach the door.