icarekit 3.5x 320mm Loupe Dental Surgical Binocular Loupes Optical Glass (Black)

The frame is a bit flimsy. The plastic is a touch too soft and distorts easily. It's not symmetric, sit with a slight tilt on my head.The plastic part holding the lenses is cheap and wobbly.The quality of the lenses is pretty good actually, no distortion even towards the outside of the viewing area.The focal length is surely not 320. I can focus around 400 mm.I would return them for that reason, but there is no better product out there for a similar price, so I will stick with them.For the price these loupes are astoninglish good, that's why I give them 4 stars.If I were a professional dentist or hygienist, I would go with a better brand. This is more for a hobbyist.