I used a silver zinger on eBay, and filled the silicone tubes with saline, which roughly doubles the electricity generated when compared to a standard ROP and completely destroys the Blakoe which only has the slightest amount of the important metals exposed. I've seen a couple guys test the current with a multimeter and the silver/saline solution combo was almost double a standard ROP and 20 times a Blakoe.
I noticed benefits from it, but nothing Penis Enlargement related. I had more energy, felt more vitalized, slightly higher sex drive and had a burning desire to go exercise/do something else physical. Never got my levels tested, but I felt better. It helped my recovery from hanging when I had the time to hang 3 hours everyday. I'd recommend one with silver for non-Penis Enlargement related reasons, but anyone who says it's going to give you a monster cock by wearing it is full of it. By careful with the silicone tubing ROPs. Mine exploded as my balls expanded and the silver rod rolled right out of my pants and down a sewer. I haven't been able to find a replacement silver rod to have an adjustable one made. The science is sound to generate electricity, but YMMV on the results of an electric current running through your balls.