I was looking for my zinc and copper rods yesterday, actually. My third set. (they don't wear out, they're just easy to misplace when not assembled) The rods need to be cleaned with a Scotch-Brite pad and Barkeepers Friend when they lose their luster or it just becomes a cock ring. The patina develops as a result of the reactions, creating a barrier against further reactions.
(That "green and crusty" stuff? It's called verdigris, and the Statue of Liberty is covered with it, not paint!)
Takes about ten minutes at most to clean, replace, and reassemble. It works best with latex rubber tubing to cling tightly to the rods so they fit snugly against both sides of the shaft. Latex reacts with the metal (some people too, unfortunately) and rubber tubing needs to be replaced regularly when it shows wear, like tires. The rods are now sold with silicone tubing now, non-allergenic, but doesn't stretch as well for snugness or cling to the rods. They provide superglue to keep the tubing in place but superglue doesn't bond silicone to metal very well so it will pop apart and fall off eventually when using silicone tubing. I wear pajama bottoms tucked into my socks as underwear when I wear it outside of my room for containment. Boxer briefs are not secure enough! Best to remove hair from the area in contact with the rods. Wear it as long as you feel comfortable, at most, I would wear it all night or all day. Only a few hours when the rods were shiny, increasing duration as they tarnished.
The principle is not an electric field that makes your cock grow...

The idea is that the minute electric current created between the zinc and copper rods and your sweat send therapeutically significant amounts of zinc and copper directly to the testes, stimulating testosterone production. I didn't try it for PE, but virility maintenance in my mid-forties. Better EQ in both stiffness and girth/glans engorgement. Permanent increase in flaccid length and girth (0.5") after a couple years sporadic use. Your mileage may vary.
I haven't worn it for a long time because I couldn't find latex tubing by the foot, because of the intravenous drug users. I don't want to buy multiple feet online because I need less than a foot per year on average, budget was way tighter last time I searched. I think the rods are stashed away, not lost so I will search. If I can't find them in a week or two, I'll probably just get a new set and stock up on the latex tubing; it can be stored for quite awhile if isolated from light, air and heat. I've had it remain supple for years attached to lead sinkers in a tackle box. But it will degrade if attached to the rods whether you wear it or not, just not as fast. Speaking of lead, don't try to do this on the cheap using copper pipe and galvanized nails, the zinc used to coat nails contains lead as an impurity. You could possibly damage your brain.
