300 Amp Crocodile Earth Clamp
This earth clamp is designed to work well regardless of where you clamp it. Compared to cheaper alternatives there is a a good copper faced contact on both the top and bottom of the jaw joined by a flexible copper strap to ensure you get a good earth when welding.
If your electrode holder looks like picture 4 then your welds will not be up to standard as you will have a poor earth.