Help info needed

Can anyone tell me what this is it came in the packet you see and  I am sure the markings are original I own a  1975 Mk3 Commando but cannot be sure i ever got this for it, it may have come with the loose parts I got with it but again cannot be sure, does anyone know the company markings and where they can be contacted and see if they have info relating it appears new and unused many thanks Chris