99.9999999999%* Pure Nickel Tabs - custom, organic, free-range lasercut tabs to make building 4p configuration batteries using 21700 cells much easier.
You are going to need a rowdy spot welder to weld 0.2mm thickness nickel consistently. Common sense required. Beware of the sparky sparks.
* Okay, so we might be exaggerating. But these are spot tested with salty waterboarding and from a known-good supplier.