Most details can be obtained from the listing's title and photos.  If a value/rating is provided, this is shown in one of the photos using a M6013 Auto Ranging Capacitance Meter

Note: Turned via a slotted shaft

I've not attempted to clean the unit in case I damage it!  Therefore, sold as seen in the photographs provided and without any confirmation of being in working order.

My father was a keen amateur radio enthusiast (G3***), hence he collected these over the years.  

Shipping quoted is within the UK only.