Button Head Socket Cap Screw is a new kind of Socket Cap Screw, it has smaller head that can solve most problem of interfere with other components.  The tool of this Button Head Socket Cap Screw  is HEX Screwdriver 2.5mm.
 
Features:
Made of stainless steel.
Compatible with structures which have 4mm holes.
Smaller head that can solve most problem of interfere with other components.
Sold in packs of 50.