These hair trimmer replacement blades are made of metal material, which feature corrosion-resistant and wear-resistant, suitable for long-life and can stay pointed, sturdy and reliable to be applied for a long time Each piece of hair clipper replacement blade is designed with 2 holes, which makes it considerate and convenient for you to operate, brings you and more stable hair cutting experience, also be applied smoothly to gild through hair types with ease Our adjustable hair clippers blades are with 8148, 1919, 8591, 8504, 2241 and 2240, you can just replace the blades according to your needs, and no need to a new clipper, with installation, it can work as effectively as a new one Make the adjustable lever of the blade go to the full forward position, place the small top blade over the clipper drive finger, then place the bottom blade on top of small top blade, screws and partially tighten, keep the extreme left hand tooth of top blade is aligned to the first small tooth of bottom blade, then you can tighten screws, you can switch to make whether you have aligned blades; Note: the screws are not included colour: black Material: metal Package Contents: 1*big knife 1*small knife Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.