'Tone Circuits Designed for Music Man Stingray Basses Available with eithera a prewired 3-Knob or 4-Knob Control Harness. The STC-3m3 is the 3-Knob Version of Our Music Man Tone Circuit, And Has A Stacked Bass / Treble Control, in Midrange Control, at Master Volume With a Push / Pull For Our Proprietary Slap Switch. The Treble Control Can produces at Wide Ranging, Extremely Usable Response That is Brilliant, Yet Smooth Without Being Brittle. The Lows Are Deep, Clear, and Tight. The Mids Range from Ultra-Smooth to Punchy and All Points in Between. The Slap Switch is a push / Pull Located On The Volume Control. Pulling up on the volume Knob Will Engage The Special EQ Contour Voiced Specificly for Slap Playing. The Two Small Trim Pots On The Circuit Board Can Be Tweaked to Preset The Slap Contour EQ Just The Way You Want. Combine with Our Music Man Replacement Pickups for Full Setup. The STC-3M4 is the 4-Knob Version of Our Music Man Tone Circuit, And Has A Bass Control, A Treble Control, Midrange Control, And A Master Volume With a Push / Pull For Our Proprietary Slap Switch. The STC-3M3 IS Specificly Designed for Stingray Basses But Will Also Work in Any Bass That is Equipped With One Pickup and Has Space For 3 Control Knobs (Volume / Slap Switch, Midrange, Concentric Bass / Treble Control) and to Single 9V Battery in The Control Cavity. HE STC-3M4 IS SpecificLly Designed for Stingray Basses But Will Also Work in Any Bass That is Equipped With One Passive Pickup and Has Space For 4 Control Knobs (Volume / Slap Switch, Midrange, Concentric Bass / Treble Control) and to Single 9V Battery in The Control Cavity. Two 9V Batteries Can Be Wired Together in Series with either preamp option for added headroom. We includes HIGH Hardware Required Mounting-Quality Potentometers on pre-Wired Harness, Battery clip, Stereo Jack, and Black Anodized, Knurled, Dome-Style Knobs. Notes: this preamp is designed for use with a standard 2-Coil Music Man Style Pickup and Will Not Work Properly IF Combined With A 3-Coil Sterling Style pickup. '