Double slits for youngs fringes, mounted

(doppia fenditura) Two parallel slits. (35mm x 0.15mm) length x width of slit in black dark plastic. White plastic frame (50x50) mm. Clear graduation should imprint on the frame. (set of 5 pcs) in plastic box/ the distance between two slits are: 0.25mm/0.5mm/0.75mm/1mm/1.25mm