High Quality Replacement Optical Glass prismatic lens plate with 3.5x magnification and a 4" focal length or working distance This comes with metal lens screws/nuts , compare the lens to Donegan Optivisor LP-10 DA-10 lens plate for $45.00) , fits many Headband Magnifier models including Electro-Optix HVM- models and will also fits Optivisor brand and many other Optivisor "Style".  Makes the perfect replacement lens for one that was lost or broken and as an accessory & Gift for someone that has an optivisor or similar headband magnifier. We also sell a set of 4 lens plates with a 1.5x,2x,2.5x,3.5x see item at the following link https://www.ebay.com/itm/115109022119