Product Introduction: Gratings with a size of 50 50mm, and the size of observation hole is 35 23mm. Combination: The combination piece consists of single slit, double slits, three slits, four slits, multiple lines, round hole, square, rectangle,triangle. The slits width of single slit, double slits, three slits, four slits are 0.06mm and the distance between 2 slits is 0.05mm. Round hole: Ø0.36mm, triangle: 0.30.30.3mm, square: lengthwidth: 0.280.28mm, rectangular: lengthwidth: 0.6 0.28mm.