Zinc inner leafs??

What is the purpose of the zinc inner leafs installed between the springs? Can you still buy them? I bought a Mopar spring rebuild kit and it came with galvanized sheet metal for the inner leafs.

it's a sliding point and is designed to reduce inner spring friction. back in the day leafs used to have sheet metal covers full of grease that you had to disassemble, clean and re-grease every so often. The zinc did away with that mess