The Barr and Stroud M-1 LED magnifier is a superb blend of ergonomics and technology. The M-1 is robustly constructed from aluminium and high grade optical plastic and is lightweight and comfortable to use. The M-1 features a 2.5x magnification main lens of 90mm diameter with a separate more powerful 4x lens of 20mm diameter. The feature that makes this product so incredibly useful is the newly developed integral LED illumination system with three brightness settings to evenly illuminate your subject matter in any lighting conditions. This is arguably the best hand held magnifier available today. Requires 2 x AA batteries.