Abstract: A fastener including a first recess and a second recess adjacent the first recess. The first recess includes a side surface defining a shape of the first recess and a stability surface oriented at an angle of greater than 1° and less than or equal to 89° relative to a major axis of the fastener.

Abstract: A screw includes a shank having a head, a point, a threaded section and a knurling section. The threaded section is located between the head and the point. The knurling section is located between the head and the threaded section. The knurling section includes a first set of grooves consisting of a plurality of first grooves and a second set of grooves consisting of a plurality of second grooves. The plurality of first grooves extends in a first angle relative to an axis of the shank. The plurality of second grooves extends in a second angle relative to the axis of the shank not parallel to the first angle. The first angle is equal to or larger than 0 degrees. The first grooves have unequal spacing. The first grooves intersect with the second grooves to form a plurality of intersecting zones with peaks and ridges of different sizes and shapes.

Abstract: The present invention discloses a screw, which comprises a shaft, a head and a thread. The shaft has an awl on one end thereof. The head is formed on the other end of the shaft and has an engagement groove. The thread is formed on the surface of the shaft and spirally extends from the awl to the head. The thread has two surfaces whose edges are connected with each other to form a cutting edge. The thread includes at least one receiving groove having a guiding face, a collecting face and a connecting face. The connecting face connects the guiding face and the collecting face to form a debris-receiving space. The debris-receiving surface penetrates the two surfaces of the thread. The connecting face has a crushing portion with a ragged surface. Thereby, the screw can provide higher locking strength.

Abstract: A screw includes a shank portion including a tapered bottom section having a tip, a head on top of the shank portion, and first and second helical threads. The first helical thread extends helically around the shank portion in a first direction between the tip and the head, and has a first end distal from the head, and a second end opposite to the first end. The second helical thread extends helically around the shank portion in a second direction between the first helical thread and the tip, and has a third end proximate to the second end of the first helical thread. The first and second directions are opposite to each other. A non-helical ridge extends around the shank portion between the first and second helical threads.