Serious Skincare Egg system for toning both sides of the face using microcurrent. I don't have any serum left but you can use your own. After I ran out of the original that came with it, I used a serum that I could just rub into my face when done. I have the instruction manual as well as the DVD which I never opened. It's easy to use, I just never take the time to do anything with it. I just tried it to make sure and it still works just fine.