Description:1. Application - Fit for all kinds of DIY, leather crafts, clothing making, or as a fastener to connect two objects. Such as thin photo albums, leather bags, wooden board connections, etc.2. Installation - Make a hole between 0.5-1mm larger than the diameter of the female rod, put the screw and nut on both sides of the locked object, and select the appropriate tool to lock it.3. Notice - The thickness of the object which is locked, must be less than the length of the screw rod + nut rod, otherwise, it will not be able to tighten.4. Advantages - Precision mechanical thread made of carbon steel material, surface treatment is black oxide, and it has high hardness.Specification:Material: Carbon SteelSurface treatment: Black Oxide Under Head Size(Female): M6 x 15mm / 0.24" x 0.59"(D*L)Under Head Size(Male): M6 x 25mm / 0.24" x 0.98"(D*L)Nut head diameter: 12.5mm / 0.49"Screw head diameter: 12.5mm / 0.49"Wrench: M4Package Content: 15 Sets x Screw Post & 1 Pcs M4 Wrench