No need to counterbore or countersink the hole because the insert has guide pilot. Used on injection moulding for tightly fixing. All nuts are made of high quality brass, which has high hardness, no deformation, and reliable for long use. Easy to install: From the moment that the insert has a valve conduit, there is no need to back-drill and counter-sink the hole. Can be installed by ultrasonic or heat in tapered bore wire, or molded in during injection., Manufacturer: Akfldms