WW2 British 3 inch mortar key No.2

This are WW2 British 3 inch mortar keys.
Not exactly true, because the British forces designed during WWII their keys in such matter that they could be used for different calibre mortars and guns.
They are mainly designed for the inserting and removal of detonators and percussion fuses.
A friend also tried it on a 25 pounder canon shell and also these accepted the fitting of these keys.
You could compare it with a ring that has a handle.
The ring is cones shapes, so it has to be fitted over a grenade head and is positioned when it can not be pulled further down.

Markings:
on both sides of the handle there are some markings.
These will probably show better when the key is cleaned.
See pictures!

Condition: light used / some rust and grease because of storage