WW2 detonator tin?

[156pff]

Hello chaps,
I bought this little tin many years ago and have seen them from time to time since.

What are they for? Someone said they are for detonators but I doubt it.

I assume the 12MB is Metal Box rather than Mills Bomb.

Any ideas?
Martin

 

[blackwatch]

hello ,

Box, spare springs, Keep pins ,washers and Insulators, number I MKI, for the 3 inch mortar

MB 12 = Metal Box Co., Hudsons ,Scott & sons Carlisle (milkcan) factory.

 

[156pff]

Thanks blackwatch