A Wartenberg wheel is a medical pinwheel that rolled into kink drawers. A handle holds a small spiked wheel that you run across skin. The feeling is a line of bright, ticklish pricks. On the inner thigh or across a nipple it can make someone flinch in a way a palm never does.

Needles should be even and sharp enough to mark sensation, not to carve. A wheel that skips or drags needs cleaning or retirement. This is not a puncture tool. If you break skin, you have an aftercare and sanitation problem.

Metal wheels take alcohol or a boil if the handle allows. Cheap painted wheels shed. Run the wheel on your own forearm first so you know what you are offering. Slow beats fast. Fast becomes a scratch.

Use

• Keep a dedicated wheel; do not share without sterilization.
• Avoid the face, throat, and broken skin.
• Pair with a blindfold if you want the startle without extra force.
• Store the head covered so it does not poke a bag.