A slotted set screw includes a shank, a slot, a cut metal waste storing recess and an outer thread portion. The slot is provided an end of the shank and includes an opening and a slot bottom surface. The cut metal waste storing recess is provided on the opening of the slot and includes a first vertical wall, a second vertical wall and a horizontal bottom surface. A first horizontal bottom edge connects between the first vertical wall and the horizontal bottom surface while a second horizontal bottom edge connects between the second vertical wall and the horizontal bottom surface. An included angle is formed between the first horizontal bottom edge or the second horizontal bottom edge and a longitudinal axis of the slot less than a right angle. In an embodiment, the bottom surface is lower than a level of the slot bottom surface in a vertical direction.

A recessed head screw includes a shank, a head, a drilling portion and threads. The head includes a top face where a socket portion is formed. The socket portion has a driving recess and a driving socket formed between the driving recess and the top face. The driving socket communicates with the driving recess. A diameter value of the driving socket is a maximum circumscribed circle diameter value of the driving recess plus a value within 20% of the maximum circumscribed circle diameter value. When a driving tool engages the socket portion, the driving socket can be in close-fitting engagement with the driving tool to increase the engagement between the driving tool and the head and prevent the screw from falling off the tool easily during the driving action of the tool, thereby delivering a full driving force to the head to improve the working efficiency and smoothness.

A fastener comprises a threaded shank extending along an axis between top and bottom ends and a semi spherical body affixed at the top end of the threaded shank. The fastener further comprises a head having a receptacle adapted to closely surround the semi-spherical body, the head being pivotable about the semi spherical body and rotatably fixed relative to the semi spherical body about the axis of the threaded shank and a drive disposed on the head adapted to receive a tool for rotating the head and the threaded shank about the axis of the threaded shank.

A security fastener for use with a corresponding driver, the fastener comprising: a shank defining a longitudinal centre axis; and a head having a face for mating with a corresponding security bit of the driver, the face including at least one recess for receiving a corresponding projection of the bit, wherein the head has: 1-fold rotational symmetry about the longitudinal centre axis of the shank; and a maximum of 1 mirror plane containing the longitudinal centre axis, such that mating of the corresponding projection of the driver with any of the at least one recesses is achievable only when the driver is in a single angular position with respect to the head, wherein the face comprises a first surface and the at least one recess is defined within the first surface, further wherein the longitudinal centre axis intersects the first surface.

A screw head bush for a screw, wherein the screw head bush has an external portion and an internal portion following the external portion, wherein the external portion has a larger diameter than the internal portion and the external portion is configured essentially as a truncated cone tapering towards the internal portion and the internal portion is configured as engagement geometry for the rotationally fixed accommodation of a screw head drive.

A screw head bush for a screw, wherein the screw head bush has an external portion and an internal portion following the external portion, wherein the external portion has a larger diameter than the internal portion and the external portion is configured essentially as a truncated cone tapering towards the internal portion and the internal portion is configured as engagement geometry for the rotationally fixed accommodation of a screw head drive.

A screw head bush for a screw, wherein the screw head bush has an external portion and an internal portion following the external portion, wherein the external portion has a larger diameter than the internal portion and the external portion is configured essentially as a truncated cone tapering towards the internal portion and the internal portion is configured as engagement geometry for the rotationally fixed accommodation of a screw head drive.