Hello Frank,
Yes, sorry, but I don't have a spare M87.
My second one is a 109 from the mobilization, which was originally an M95, whose B.A. XIV replaced the M91 post-side chinstrap with an M87 hook-type one.


The old brand of the M91 side post is clearly visible.

This helmet was a Baden 109 LGR model since 1895, because it has a spike with five ventilation holes and no Perlring, and a ventilation flap on the top of the rear spine. It had side-posts, which were exchanged for M87 hooks in 1914, and its plate has eyelets and leather corners.
In 1914, this old helmet was brought back into service, and for reasons of ersatz and urgency, its old M87 chinstrap was fitted to equip a Reserve Grenadier of this regiment. (The first two battalions of the 109th Infantry Regiment retained the "Grenadier" designation, but not the third, designated "Fusilier." This is why the marking is specific to this regiment: IGBRR109 for 1st Grenadier-Reserve Battalion-Regiment 109.)

I am showing this helmet again here because of its M87 chinstrap, the mechanism of which I was able to describe in detail.
All my best wishes for good luck, Frank. If I happen to see one of them, I'll be thinking of you.
