Stainless steel bolt and screw types

Raised Hexagon Washer Head bolt

Flat Head (100) Countersink) screw

A Thin section of a hexagonal prism
with a spherical cap. mounting a 
thin cylindrical section greater than
the A/F dimension of the hexagon

Large head distributes pressure over larger and less angular surface. For use with thin aluminum soft plastics.

Clutch Head bolt

Flat Head (Undercut) screw

A Countersunk slotted head with two quarters of the head removed so that the screw may be driven in one direction only 

Standard flat head screw with lower one-third of countersink removed for production of short screws. Permits flush assemblies in thin stock. 

Round Pan Head

Flat Top Binding Head screw

A Thin cylindrical section, the edge remote from the shank being radiused and surmounted with a spherical cap.

Gives large bearing surface with low head height, but poor slot contour. Almost obsolete due to popularity of truss head. 

Shallow Cup Head bolt

Hexagon Head (Finished) bolt

A spherical cap with a flat face adjacent to the shank.  

Integral washer under head is slightly smaller than diameter across flat; protects the work against disfigurement by head corners during tightening  

A section of a square prism often chamfered on its upper surface. 

Domed Hexagon locates sockets wrenches quickly. Slot permits screwdriver operation. Combines good appearance, fast assembly protection to work surfaces.

12 Point Head bolt

Binding Head bolt

A lightweight head, largely designed for aircraft use with A/F and A/C dimensions much smaller then the hexagon head on male fasteners of corresponding thread sizes.

Undercut beneath head binds and eliminates fraying of standard wire in electric work. Ample bearing surface.

Flat Fillister Head bolt

Similar to standard fillister but without oval top section. Suitable for counter bored holes requiring flush screw.