Flat Head Self Drilling Screw (SJ-3001)

The flat head is also called countersunk head(or abbreviation as CSK head), this is probably one of the most common head types for fasteners.

But there are still differences under such division.

Sometimes people confuse the "bugle head(see SJ-30014 below)" with it.

A concave shape below the screw head is the most identifiable feature of the bugle head screw, they are usually used to fasten the plasterboard or gypsum material(hence, we call them "drywall screw" or "gypsum screw").

Under some of the flat head screws, you can find 4~6 ribs(or nibs) around it, they are commonly used on double panels (metal+PVC).

They are also knowns as "window screws" or "PVC screws".

Flat Head (SJ-30011)	Flat Head (SJ-30012)
Flat Head With 6 Ribs (SJ-30013)	Bugle head (SJ-30014)

Small Flat Head (SJ-30015)