What do you mean by shoulder harnesses?
These fur pieces have those grooves on them to allow for holding shoulder straps securely in place. If you have a figure with a shoulder strap (like the ones with pegs that you can attach hooks or weapon holders or quivers to), the strap will be held in place very well by the fur pieces. In the picture you posted in the first thread, these grooves can be seen on the right side of each piece.
