M4 screws are typically used in the manufacture of small items of electrical equipment, laptops, cameras and mobile phones. The “M” designation for metric screws indicates the outer diameter of the screw in millimeters, so for an M4 screw, the outer diameter is 4mm. However, in practice the actual diameter might be between 3.9mm-4mm due to manufacturing tolerances. The head is standard star head and pitch is also standard 0.4mm of both Nut and Screw to make them compatible with existing appliances hence we can use it in the equipment like laptop cameras and also for attaching caster wheels in robotic projects. The length of the screw is 12mm.
 
Specifications
M4 Type
12mm in Length
Button head screw (Star)
Each unit has 4 Screws
 
Package Contents
4× M4 12mm Screw