The MONARCH Angled Prism Unit uses Nikon's original total reflection prism. By ensuring that all reflective surfaces are completely reflective, it reduces the loss of light and provides a bright, clear view. Thanks to a newly-designed and highly reliable sleeve mechanism, the MONARCH Angled Prism Unit can be connected to different MONARCH Objective Units with minimized optical axis deviation. Different eyepieces are also easily attached using a newly developed CircuLock System. With the CircuLock System, a collet chuck and ratchet mechanism secure the eyepiece to the Prism Unit and make it easy to attach/detach.