These are Surgitel 5.5X Advanced Ergo Deflection loupes . Interpupillary distance is 62mm. Working distance is 20 inches and can be easily changed. They have never been used. Mounted to the Titanium Aero frame in tortoise shell. This frame is adjustable for Vertical height and divergence. Measure your IP with IPhone app “EyeQue” - see pics for reference. Vertical height adjustable. Never used perfect condition. $3500 Loupes. Same day shipping.