This is a nice quality (UK sourcsed) 7/8" handlebar exhaust valve lifter. It is of the type normally fitted to all Norton single cylinder models (including SOHC models), and is commonly used to allow the exhaust valve to be llifted so the kickstart can be eased past compression to help starting.
As you can see from the accompanyning photographs, we also offer two alternative designs of exhaust valve lifters - one with a longer arm and one with a short stubby lever. They all do the same job, so it is really personal preference which you prefer.
See also the Cambox section of the catalog to show other SOHC Exhaust Valve Lifter items we manufacture, or the OHV section for OHV exhaust lifter rockerbox arms
Note: unfortunately we have not been able to find a source of 1" diameter exhaust lifter levers yet - if you know of anyone, we would be glad to hear. Eventually, we may manufacture a small batch ourselves