It's basically the Hot Tubes and the Crayon together in one pedal. More info here.
Electro-Harmonix unveils the new Hot Wax pedal which combines the Crayon full-range overdrive and the Hot Tubes, a reissue of the classic 1970s CMOS overdrive. Each pedal can be used individually or they can be stacked with the Crayon driving the Hot Tubes to create new tones and textures.
Independent Volume and Drive controls are included for both overdrives as are dedicated pop-free footswitches and effect status LEDs. A master EQ section featuring Bass and Treble, plus a Blend control which lets the player mix in their dry signal, provide superior tonal control and flexibility making the Hot Wax ideal for guitar and bass.