Cherry G84-4700

price

100% of the reviews on Amazon.co.uk give this product a positive rating.

It's a programmable keypad, which gives you much greater control over input. It can sit next to your main keyboard, not taking up too much space, but giving you vastly increased key entry capabilities

Unlike many of the other Cherry programmable keyboards, it stores the key definitions in the PC (i.e., in Windows), not in the device, so it's not usable in Linux