Shear off nut made form steel or high tensile steel, there is hexagonal head with thin neck with conical shape covered threaded part. Once you fasten the nut with spanner fully beyond further tightening the hexagonal portion of the nut will be sheared [cut due to the thin portion of the bottom circular piece held with hexagonal head]. Once it [shears] breaks the bottom circular taper portion only held with the Nut’s threaded end.
Once it is fastened the circular shaped nut cannot be opened or unscrewed thus making very difficult by ordinary tools. To open the nut one needs severe chiseling on the circular head. So it is called a special nut as theft safe nuts. Such special bolts are normally used where the sign boards or expensive high way signals are more prone for theft.
There are screw are also available once you fasten it you cannot unscrew it due to special shape of the screw groove.
This are mostly used which things are installed in public place and possibility to damage and theft. Also installed in that place however once the things are installed and not to need remove until the things are damage or remove or dismantle.
Tejas Fasteners provide break through nut Diameter 8mm to 12mm. we can also manufacturing as per customer convenient dimension.