Seamine detonator?

[Michel]

This was described as a seamine detonater maybe someone has an ID. Stenciling on the body says " .W.5.40 Lot 100" pressed into the metal "Is 742 /l\". Dimensions 53 x 103 mm. Copper.
So U.K. made 5 1940.

 

[Natter]

Parts of a "Detonatorholder Mk I" for british seamines (used in several systems, like the Mk XIV, Mk XV, Mk XVI, Mk XVII...).

 

[Michel]

Exellent !!