A smooth base provides more contact with the mating surface than weld nuts with projections.

Weld these nuts to uncoated steel surfaces.

These nuts can be used in channels and tight spaces where round-base weld nuts won't fit.

Weld these nuts to stainless steel surfaces.

A smooth base on these metric nuts provides more contact with the mating surface than weld nuts with projections

Projections on the base concentrate the weld and provide room for heat to dissipate.