A noninvasive, hand-held, manual device intended to be used during an eye examination to determine objective and subjective convergence points, examine accommodation, and determine the master eye. Often called a Royal Air Force (RAF) convergence rule or RAF binocular gauge, it consists of a rule (typically 50cm long and multi-sided for taking different measurements) with a sliding test panel (typically multi-sided to allow different tests); it may have a handle at one end and a Y-shaped face rest at the other. Testing includes measuring the near distance at which, e.g., double vision is observed. This is a reusable device.