Chris King FunBolts are used primarily with their single-speed hubs. However, it's possible to use them with a standard ISO Disc Rear hub because those have an axle with removable QR adapters that are threaded into place. Why would you want to use FunBolts you might ask? They offer a bit more security than quick release skewers in terms of clamping force into the rear dropouts.
Chris King FunBolts are hollow and made from stainless steel and use an aluminum cap sleeve to distribute even pressure across the face of the dropouts. They require an 8mm hex wrench to torque them into place.