I really couldn't see the backmark on Marc Parker's button but he has the backmark written out in his article. I think he said that particular backmark with the MG instead of MFG is 1840's and 50's which is correct. I've dug buttons in civil war camps with the backmark shown on the cuff but have also seen that backmark on buttons from the late 1800's as well. Anoter difference in the buttons is that Marks is a 2 piece, face and back. While the ones in the auction are 3 piece , face, back and rim, staffs.