These are digital versions of the classic grey and black-faced 80mm speedos and tachos seen on the Meriden Triumphs, BSAs and most British bikes from the 1960s through to the 1980s.
The range has recently been expanded to include replicas of even earlier British machines. The new digital chronometric uses a turned case with a screw-off bezel just like the original, but the loom wiring to connect it to the bike is hidden in a false cable, thus keeping the period look. And yes, they work with most 12 volt systems.
Priced from £179.99 (£234.99 pictured). More information from the website www.puca.co