Patent ID: 8678732

Claim:
An accessory and frame system for fixing an accessory on a metal frame for doors and, windows, the system including; a screw having a head and a self-tapping threaded stem; an accessory and a frame having adjacent walls formed with corresponding coaxial circular through holes respectively for insertion of the screw and for screwing of said self-tapping stem; said self-tapping stem of the screw having a thread with a constant pitch; an end of said self-tapping stem opposite to said head of the screw being conical; a ratio between the external diameter of the self-tapping stem of the screw and the diameter of the through hole of said wall of the frame is between about 1.4 and 1.25; and a ratio between the diameter of the through hole of said wall of the frame and the thickness of said wall is between about 2.5 and 5.5; and wherein said screw has a guide portion having a cylindrical surface between said head and said self-tapping stem.