Disk Electrode is all stainless steel. This makes it among the most intense electrodes.
The slightly concave disk head has a few ways to use it. Use it on its side, perpendicular to the skin, it can feel like a knife cutting, though there’s no danger of that with its rounded edge. Hold it flat above the skin with its concave surface toward the body. Held at the right height above the skin just before the spark would jump, its wide surface area produces a coronal discharge that makes your hair stand on end. So its possible to feel the electrical aura before the spark jumps, making a very interesting and hair raising sensation.
Advanced tip: Think electricity and water don’t mix? If you practice advanced violet wand techniques, trying using the concave surface to push an ice cube around on the skin. You can also attach a round conductive rubber TENS pad to the round surface and have a non-grounding electrode. Disk head is almost 30mm in diameter, but even larger TENS pads will hold nicely.