The mine itself is a cardboard cylinder to avoid detection by metal detectors.[1] The mine trigger is a hollow ebonite rod on top of the mine, which in later versions is replaced with a circular steel pressure plate to increase the trigger area.[1] Explosive filling is either 50/50 pentoliteorRDX/TNT. To save the mine when not in use, a wooden plug is inserted in its fuse well.
The mine is activated by downward pressure on the top of the mine, for example by a soldier's foot.[1] This forces down the ebonite rod on top of the mine which goes through the mine collar below it.[1] This releases retaining balls that the collar was holding which in turn release the spring-loaded striker.[1] This then pierces the No. 99 MK I detonator which activates booster charges on either side of it, detonating the mine.[1]
To arm the mine, first off, if the wooden safety plug is still in the fuse well, remove it.[1] Then insert the No. 99 detonator, and then insert the ebonite rod containing the striker (among other things) in the fuse well above the detonator.[1] Make sure that no pressure is applied to the rod after insertion to avoid accidentally setting off the mine.[1] To disarm the mine do the opposite of arming: remove the striker and then the detonator.[1]
