1.Made of carbon steel nickel-plated.2.M8 Thread.3.Suitable for Aluminum Profile 3030 and 4040 Series4.Easy to be roll into T slot of aluminum profile.5.Could be used together with T screw/hex screw Specification:Main Color: Silver ToneMaterial: Carbon SteelFinish: Nickel PlatedModel: 3030/4040 Series-M8Length: Approx.20mm / 0.79"Width: Approx.12.4mm / 0.49"Thickness: Approx.13.4mm / 0.53"Package Content: 15 x Spring T-Nuts