This dual heater works great in our Runa the Wolf, Künderin the Dobie, and Hulda the Mare dual hole sleeves. Effortlessly bring your sleeve to body temperature with these dual USB heating probes. Designed for convenience, this advanced warming device quickly and evenly heats the interior of your toy enhancing comfort and realism. Features automatic temperature control, when your heating sticks cool to a certain level, the temperature control device will automatically heat them back up. High temperature power outage protection, even if you forget to turn off the power, it will automatically power off when the temperature exceeds 110F, so no worrying about overheating. These heaters are also waterproof, there is a waterproof rubber pad between the heaters and the charging lines. Even if submerged in water, it will not damage the heaters.