1set mean: 1pcs bolt + 1pcs nut.
Material:NUT:brass;Bolt:304 stainless steel.
Size:
brass nut:ID*Height*OD.
Bolt length=brass nut height +(1mm or 2mm).
eg:M2x3x3.2 30set
You can get brass insert nuts( M2x3x3.2 30pcs )and bolt( M2*4mm 30pcs or M2*5mm 30pcs Random delivery).
If you want another bolt length,please tell us.