Hi,
Here is a time and percussion fuse-detonator 24/31 mm A Mle 1918 (graduated from 0 to 31 seconds).
It's a common fuze but this one is stamped with two interresting markings : INERTE and INSTRUCTION.


Scheme of this fuze :

And explanations on this website :
http://www.passioncompassion1418.com/decouvertes/english_fusees_collection_fr.html#Fus2431AMod1618
Stephan
Here is a time and percussion fuse-detonator 24/31 mm A Mle 1918 (graduated from 0 to 31 seconds).
It's a common fuze but this one is stamped with two interresting markings : INERTE and INSTRUCTION.


Scheme of this fuze :

And explanations on this website :
http://www.passioncompassion1418.com/decouvertes/english_fusees_collection_fr.html#Fus2431AMod1618
Stephan