The present invention relates to a drive element (8) which has an internal driving profile (9) that defines a profile axis (P.sub.I) and has, on its inner side, a plurality of concave drive faces (6) arranged in a manner distributed regularly around the profile axis (P.sub.I), between which a planar or convexly curved transitional faces (7a) are provided, or which has an external driving profile (9) that defines a profile axis (P.sub.A) and has, on its outer side, a plurality of concave drive faces (10) arranged in a manner distributed regularly around the profile axis (P.sub.A), between which planar of convexly curved transitional faces (7a) are provided.

Various embodiments described herein provide a fastener system having straight walled driving surfaces that provides a reliable stick fit feature, while also improving stability of engagement between the system components. A feature of the new system is to allow stick fit engagement of existing standard straight walled drivers in the new system.

A T-Nut comprising a tubular body attached to a flanged head is provided. The tubular body includes a bottom portion of constant diameter and an upper neck portion with a neck diameter that gradually increases as it approaches the flange head. Additionally, the bottom surface of flange head of the T-Nut may be recessed inwardly towards the top surface of the flange head to create circumferential concave cavity underneath the flange head, which will allow the flange head to envelope any portions of a washer or casing that may be above the surface of the material being joined.

A locking element is configured to be used with a polyaxial bone anchor. The locking element including a central axis, a bottom side, a top side opposite to the bottom side, and a peripheral surface portion that extending completely around the locking element that has an external thread. The bottom side defines a first recess facing toward the bottom side for accommodating and applying a force in a direction toward the bottom side to at least the portion of the head of the polyaxial bone anchor. The top side defines a second recess having a non-circular cross-section in a plane perpendicular to the central axis for torqueable engagement with a driver.

A screw includes a threaded shank and a head with a first surface. Communicating sockets formed in the first surface include a Pozi-type socket and a drive socket. The drive socket includes rounded portions, arched portions alternating with the rounded portions, and a conical portion connected to the rounded portions and the arched portions to define a first reference line and a second reference line parallel to a central axis of the head. The rounded portions are inclined outwardly from the first reference line, and the arched portions are inclined outwardly from the second reference line. Thus, a first room enclosed by the rounded portions and the arched portions increases gradually towards the first surface. By a combination of the above sockets, the head cooperates with different driving tools for delivering driving force efficiently and is more convenient to use.

A hose adapter may include an outer tube, an inner tube, a hose connector, and a hose. An inner peripheral ring protrudes from the inner periphery of the outer tube while an expanding ring portion protrudes from the outer periphery of an end of the inner tube. The outer periphery of the inner tube further has a first peripheral recess, a second peripheral recess, and a first outer thread, and a first O-ring and a second O-ring are respectively disposed on the first peripheral recess and the second peripheral recess. The inner tube is inserted into the outer tube, and the expanding ring portion is abutted against the inner peripheral ring, and the first O-ring is coupled between the outer tube and the inner tube while the second O-ring and the first outer thread are adapted to pass through and be exposed out of the outer tube.

A self-penetrating thread forming and flow drilling fastener for thick materials with a generally cylindrical partially threaded shank, a drive system at the first end of the shank and a flow drilling tip at the second end of the shank. The flow drilling tip is sized larger than the minor diameter of the threaded shank but less than the major diameter to control installation torque enabling installation into thick materials with greatly reduced risk of torsional failure resultant from a decrease in torque. The flow drilling tip and threads may be a variety of shapes or thread types based on the substrate material the fastener is installed into.

A screw having stacked screw heads includes a screw shank portion with a thread and a screw head portion rigidly connected to each other. The screw head portion is driven to bring the screw shank portion to rotate. The screw head portion includes a first screw head and a second screw head. The first screw head has a first shaped groove on its top plane to receive an operating torque. A neck portion is connected to a bottom plane of the first screw head and a top plane of the second screw head. The second screw head has a second shaped groove on its top plane. The neck portion or the connection between the neck portion and the first screw head or the second screw head has lower torsional endurance than each of the first screw head and the second screw head.

A multipurpose screw is provided. The screw comprises: a head having a tool engaging formation, a self-drilling drill tip, and a shank extending between the head and the drill tip. The shank includes a threaded portion and an unthreaded portion. The threaded portion includes a major thread extending from the drill tip. The ratio between the major diameter of the major thread and the pitch of the major thread is from 1.2 to 2.4.

A screw has a screw head and a shank extending downwardly from the screw head. The shank has a threaded segment, a cutting segment, and a tapered segment sequentially arranged downwardly, a thread spirally surrounding an external surface of the shank from the threaded segment to the tapered segment, multiple cutting ribs arranged around the external surface of the shank on the cutting segment of the shank, and multiple chip recesses formed between the cutting ribs. Each of the cutting ribs has a rounded crest to enlarge a drill hole and to reduce a resistance formed between the cutting ribs and the workpiece during drilling. The screw can be easily screwed into the workpiece with less driving force.