21mm Head M6x40mm Male Threaded Knurled Thumbscrew Grip Knob 5 Pcs Product Name : Thumbscrew Grip Knob;Material : Metal, Plastic;Type : M6 x 40mm Thread Dia : 6mm / 0.24";Thread Length : 40mm / 1.6" Head Dia : 21mm / 0.8";Total Length : 54mm/2" Head Type : Thread Screw;Color : Black, Silver Tone Weight : 62g;Package Content : 5pcs xThumbscrew Grip Knob