Thumb Screws Assortmentyou will receive 10Pcs M4 x 10 mm + 10Pcs M4 x 25 mm + 10Pcs M4 x 40 mm. Total 30 pieces 25 Male thread star knobs. which can be installed in any place you need. and meet your daily use and replacement. Easy to install the knob hand tightening screw adopts a screw-in design. which is easy to install; Round shaped knurled head. fastening. locking. adjusting effect. Nice craftsmanship the surface of the grip thumb screw on type round head is smooth. the thread is neat and uniform. without burrs. making the installation effect more tight. Plum Hex Shaped Hand KnobsBlack Fastener Clamping Knobs are made of quality plastic and carbon steel. with good hardness. strength. corrosion resistance and wear resistance.