1.The 40w flyback transformer used in the Co2 laser power supply / laser engrave machine.2.The 40w flyback transformer only suitable for 40W Co2 laser power supply.3.The 40w laser power supply has 1 piece flyback transformer. so you only choose 1 piece for your laser power .4.Please check the install schematic diagram.5.The screw is for install fixed on the laser power box.6.If the laser engrave machine no laser beam come out . Then you need replace a new flyback transformer for the laser power.7.If the Co2 laser engrave machine laser power is weak , and it can\'t cut through any materials . Then you can adjust the laser power to maximum value. at the same time . you check the machine ampere.If the Am indicator is still less than 8 Am. Then you need replace a new flyback transformer for the laser power supply.