Diftech Nut Cap 8x12

M8x1.25, 8mm Metric European Copper Exhaust Nut with Locking Slit

Diameter: 8mm
Collar Diameter: 11.6mm
Thread Pitch: 1.25
Reduced Wrench Size: 12mm 
Height: 8.5mm

DIN 14441 / Steel Nut with Copper Plating

Also known as slotted nut, copper hex lock nut or split copper nut. Suitable for extreme heat, example: exhaust manifolds. Temperatures -94 to 750 Fahrenheit

The locking mechanism for this nut is based on the slit at the base of the collar. Before tightening onto a screw or bolt, the slit is collapsed. As the nut is tightened onto the fastener, the slit expands, pinching the threads of the screw or bolt and locking the nut in place.