Material : Nylon, Thread: M3(3mm) 260PCS M3 Male Female Nylon Hex Spacer Standoff Screw Nut Threaded Pillar PCB Motherboard Assortment Kit (Black,)includes 13 kinds of types Package:packed in a plastic box, good for storage and difficult to be damaged Nylon has the characteristics of Non-Magnetic, thermal insulation, corrosion resistant. meet you different needs Application in electronics, computers, PC board, DIY hobby Features: Made of nylon, resistant to acids, alkalis, insulation and signal interference 260 sets, 13 types to meet your different installation needs. Well made,with very clean threads and no spikes for perfect use. The PP organiser is arranged in a logical order and can be easily accessed. It is very easy to store and carry these small screws. Ideal for mounting between circuit boards and machine boards.