'flygrimm' - MasterChief's photo shows the correct type of Rod for your Mark IV - MH.
The Rod you now have is a 'modified' Mark I - MH Rod.
Originally the Mark I Rod Head was larger. In fact, it was larger than bore diameter and required an implement on the threaded end in order to knock out a stuck case or clean the barrel. IIRC - The 'cross-hole' in the head was for an implement or punch to be inserted to serve as a handle.
I believe a lot of the 'modified' Mark I - MH Rods have come from the Nepal Cache (of badly stored BritishArms). I don't know if the Heads were ground to smaller diameter in Britain or in Nepal. (Reducing the head diameter allowed the head to enter the bore so the rod could be used to clear a stuck case - Good Move!).
I was happy to get one of these 'modified' early rods a number of years ago for an Enfield made (1873) Mark I Martini-Henry, that was missing its Rod.
A loose unaltered Mark I Rod is an extreme rarity.
(Photo 1. Mark I rod & jag. 2. Mark I 'modified' Rod.
Attachment 87699Attachment 87700