Tins of grease always used to have a disk of metal with a hole in the middle sitting on top of the grease. To fill something you rested it on the plate and pushed and the grease oozed upwards.
Looking on line to show a friend I can't find a single illustration of a can with the plate - do they still exit ????
Looking on line to show a friend I can't find a single illustration of a can with the plate - do they still exit ????