The welding electrode is SMK | Air & Spring Lower Holder for Nut Welding

Lower Holder for Nut Welding used by fitting to Straight Holder.
Use this product with Spring, Bakelite Plate, Speed Controller and Spring Cap.

As the guide pin is pushed by air and spring, the air pressure can be reduced compared to a holder only using air, and spatter scattering is reduced.

By using air together, spatter inside the holder can be removed and the electrode can be cooled.