Electronic magnification for reading and close work, in screen sizes from 3.5 to 8 inches handheld through to desktop units. All offer adjustable zoom, high-contrast colour modes and LED illumination, with rechargeable batteries on the portable models.

Screen size is the main trade-off: smaller units go in a pocket for menus, labels and price tags, larger ones suit sustained reading at a desk. Many users end up with one of each. If you are choosing a first device, start from where it will be used most.