I could manage to take photos of the Mühlenfeld straight jacket this morning.
Here they are: The jacket consists of 2 types of leather and leather straps and two types of cloth. One seems to be a type of canvas, the arms seem to be a type of 2-3 layers of cotton. The mittens seem to be a mixture of layers of cotton and leather. The arms will be strapped at the side in kind of "strapping sleeves". Three of the straps are marked with "FR.AUG.MÜHLENFELD GMBH BARMEN"
wich means: FR. = Firma (Company); AUG. = August; GMBH = Gesellschaft mit beschränkter Haftung (limited company);
As I could not see the pictures in the preview, I hope they arrive and you can see everything.