Pure Nickel Battery Strips - 99.6% Purity 100 pcs. have tested them to see how clean they could be but they are magnetic and I have no problem soldering them or running current and voltage through them. The ones I got were 0.09mm x 4mm x 100mm, that was good for me because I was really looking for 0.08 x 3.175 x 100mm, that was the closest I could find.