based on an old Malvern Star saddle bag.
two straps hold it closed and also attach it to frame, saddle, wherever.
stiff leather for front and back
softer leather for sides
the brand says
which means "martial"
and was done with an antique Japanese cake* branding iron.
these were used so that if any of your cakes strayed
into another farmer's herd you could tell which ones were yours.
here's my preferred position
since hanging from the saddle obscures the rear light.
could also hang it sideways
from the top tube.
* I think they were used on dorayaki.