I'd required

Any idea,s what these are off. Thanks

These are primers / safety fuse couplers for British “switches” (firing devices).
There were plenty of variants and most were made to accept the threaded one on the right which has the small sprin-claws to secure safety fuse in case it was inserted. Otherwise only a detonator was sled over this part before it got installed into a demolition charge.

Examples (image source: internet):

The smooth type (variant):


Many thanks for your quick reply.

think the US also used very similar

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Pete, the US types are threaded and somewhat different (image source: internet):

Known as “base couplers”. Contains roughly the equivalent of a shotgun primer. When ready to use you break off the protective plastic cap, underneath is a rubber covered nipple, onto which you crimp a non-electric blasting cap. The rubber lining makes it moisture resistant.

Thank you all.

The British ones are known as ‘Snouts’ of which there are 6 known varieties. There are Flanged, Flanged and threaded, and threaded versions. We started out with flanged on the early switches and in 1940 moved over to threaded, for subsequent switches that were introduced.

thanks Alex

Does anyone know the exact designation of the one pictured on the left of the first image?

U.S. M1A1 Pressure Firing Device screwed into a “Pineapple” [Mk 2?] frag grenade.
(File photos, no idea where they came from).

Pressure Firing Device M1A1 03 Attached

The base couplers would fit into grenades, TNT blocks, mines, etc. Somebody was thinking for a change and made it pretty universal.