Hard Candy is an original Red House filter part that is incorporated into the circuit of a guitar or bass, and was jointly developed at the request of Natori Otozo, the manufacturer of Occult Dip Box. It can be considered an installed version of Occult Dip Box.

While the basic direction is to aim for the vintage tone of this product, the Hard Candy has been tuned for Red House to provide the optimal tone for guitar, bass, single coil, and humbucker.

All versions fully demonstrate the core effect of the Occult Dip Box, which is to "reproduce rich, delicious, musical midrange without hurting the ears" and "smoothly control the unpleasant parts that remain even after applying electronic EQ". ON/OFF control is also possible with a pot or mini switch.