A weld nut is a special type of nut specifically designed to be welded to another object. There are various types for different applications.
Size: M4-M16
Width across flat: as per size
Thread type: metric corse/fine right-hand thread
imperial thread is available upon request
left-hand thread is available upon request
Material: steel
Grade: 4.8/6.8/8.8/10.9/12.9
Finish: plain
Technical info: DIN 928