This is the 12 extra inserts for 6x6cm focusing screen. Black lines printed on transparent plastic base. You can just put it over focusing screen and change them easy and quickly.
Size of any square's 56x56 mm,thickness -100 microns. Comes as 2 sheets with 6 screens printed on each sheet. You have to cut a screen out of sheet on any size you want; smaller or bigger than 56x56. Price is for all 12 pieces of screens.
Use regular scissors. Special cutters not necessary.
You can use it for any medium format camera with 6x6 frame: