The new Bartolini NTMB Systems have eliminated the second module and have only the single 1-3/4 x 1 x 1/2 module. There is also a weight saving on the new systems of 20 grams.Control Configuration Volume (Active/Passive Push-Pull) Blend Treble/Bass Stack Mid (Push/Pull Freq. Selection) A Pre-Wired harness saves the time and aggravation of wiring your pre-amp and pots into your instrument. They feature our industry leading pre-amps and premium audio-quality potentiometers with smooth control and ready for years of rugged use.