uxcell Plastic Knurled Head Clamping Knob Jig M4x40mm Male Thread 10pcs Black Product Name : ClampingKnob;Type : Screw On Head Diameter : 15mm /0.6";Thread Size : M4x40mm/0.16" x 1.6"(D*L) Total Height : 52mm / 2";Material : Metal,Plastic Color : Black;Weight : 62g Package Content : 10 x ClampingKnob