Panasonic 3V CR2450 Button Cell Battery
Sold individually these batteries will suit many of the welding masks available. Typically called a button cell these flat cell batteries are 24mm diameter by 5mm in height.
These lithium button cells typically provide 3 volts output.
We have found the Panasonic brand button cells to work well in the automatic welding masks, better than many other premium brands, hence why we sell these Panasonic batteries, they may cost a little more but they work well.
Please be aware the photo is relatively old typically the "sell by" date on the currect stock is 2034