Songzi Optics (5X 6X Optional) Binocular Medical Surgical Dental Loupes with LED light for Surgery Vascular anastomosis operation Others (working distance: R(420mm), Magnification:6X) Magnification:5X , Field Of View: 60mm,Certificate: ISO9001:2008,CE.Viewing Angle: 20-150. magnification:6X , optical system: prism optics,Field Of View: 55mm. LED headlight High intensity;15000-30000Lux,Continuous run-time: 7 hours,Light head weight: 9g,---Battery pack weight:100g,--- LED bulb:1 W,---Charge voltage:AC110V/240V/50-60Hz, 4 kinds of working distance : S(340mm) ,R(420mm) ,L(500mm) ,XL(550mm) How To Choose Your Loupes Determine your working distance, which will also automatically determine your field of view. While working on a friend or family member have someone measure the distance from your eyes to your patient's : this is you working distance. Choose the distance that is closest to the selection we offer. IF you are a dentist , your height is in the range from 160cm to 180CM,we recommend R(420mm) working distance.IF you're a surgeon, you are sitting while working, your height is from 160cm to180cm, we recommend working distance R (420mm ). IF you are standing while working, your height is from 170cm to 180cm, we recommend L (500mm) working distance, even XL(550mm) working distance will be OK.