Fountain Pen Revolution
This the same loupe we at FPR use for all of our nib inspecting and tine tuning. We tried a bunch of the more expensive ones and honestly prefer this model because of its wide 25mm lens and convenient light. It is listed by the manufacturer as having 40x power but, based on comparison we think it is more like 15x, which is plenty powerful enough for nib tuning.
Includes 3 already installed LR927 batteries, protective case and tool for changing batteries.