Heavily upgraded 8-128-R replacement part to fit all Marvel 8, 8MKI and 8MKII bandsaws. This screw is the adjustment at the upper and lower blade guide posts that allows the user to adjust and maintain perfect alignment of the blade for straight cuts. Made of steel, with knurled edge and slotted front, this thumb screw is a necessary upgrade for all Marvel 8 band saws. Alternate part numbers 8D128DR.