This is for a set of hold down clamp for use with the T-slot rail These clamps are useful in many wood and metalworking applications for holding, positioning and securing work. Apply clamping pressure anywhere along the recessed T-rail. Slips into the T-rail and attaches quickly by turning the knob nut. T-screw and threaded rod have 8mm thread. Very versatile! Also ideal for mounts and fixings. Features: This is for a set of retainer clamp for use with the T-slot rail These clamps are useful in many wood and metalworking applications for holding, positioning and securing work Apply clamping pressure anywhere along the recessed T-rail Slides into T-rail and fastens by turning the knob nut The T-screw and threaded rod have an 8mm thread. Very versatile! Also ideal for mounts and fixings Features: Main material: metal Main color: silver Thread Size: M8