Package Content:
M5 x 20mm---- 10pcs -- Full thread,
M5 x 25mm---- 10pcs -- Full thread,
M5 x 30mm---- 10pcs -- Full thread,
M5 x 35mm---- 10pcs -- Full thread,
M5 x 40mm---- 10pcs -- Full thread,
M5 Hex Nuts --- 30pcs.

About Countersunk Screws:
A countersunk screw is a type of fastening that sits flush with the surface of the material it occupies.
These screws typically are used so that you can cover them easily with either a screw cap or piece of wood.
Other applications include the need for a fastening not to protrude so other objects can rest upon it stably, or to fasten it further to another object.