Specification Brand : uxcell BulletPoint1 : Product Name: Knurled Thumb Screw; Package Content: 12pcs x Knurled Thumb Screw BulletPoint2 : Main Color: Silver Blue; Material: Carbon Steel BulletPoint3 : Weight: 71g; Thread Size: M4 x 12mm/ 0.16" x 0.47" (D*L) BulletPoint4 : Total Length: 20mm / 0.79"; Thread Pitch: 0.7mm BulletPoint5 : Coating: Zinc Plated; Head Size: 8 x 12mm / 0.31" x 0.47" (L*D) DriveSystem : Thumb ExteriorFinish : Silver ItemName : uxcell M4x12mm Carbon Steel Flat Knurled Head Fully Threaded Thumb Screw Bolt 12pcs ItemPackageDimensions_Height : 13.8 centimeters ItemPackageDimensions_Length : 1.3 centimeters ItemPackageDimensions_Width : 9.8 centimeters ItemTypeKeyword : thumb-screws Manufacturer : uxcell Material : Carbon Steel MeasurementSystem : Metric MetalType1 : Zinc MetalType2 : Carbon Steel ModelNumber : a17082400ux0028 NumberOfPieces : 12 PartNumber : a17082400ux0028 ProductDescription : Round thumb screw with flat knurled head style. Knurled head provides extra grip for manual tightening. Usually found on thumb screws, a knurled surface on the head gives a better gripping surface, making it easier to tighten or loosen fasteners manually. Thumb screws are designed to be tightened and loosened by hand. Tools not necessary for tightening or loosening Knurled Thumb Screws are installed with your fingers and are used to hold light covers in place and other ornamental products.