| Feature | harpejji® u12 | harpejji® g16 | harpejji® k24 (Discontinued) | harpejji® M5 |
| | | | | |
| Year Introduced | 2015 | 2011 | 2010 | 2024 |
| Number of Octaves | 3 octaves (like a ukulele bass) | 4 octaves (like a 6-string guitar) | 5 octaves (like a 5-string bass + guitar) | 5 octaves (like a 5-string bass + guitar) |
| Note Range | C2 to C5 (= lowest 3 octaves of g16) | C2 to C6 | A0 to A5 | C1 to C6 |
| Number of Strings | 12 strings | 16 strings | 24 strings | 22 Strings |
| Number of Frets | 15 frets | 19 frets | 15 frets | 19 frets |
| Fret Type | Pepperoni-Tone® frets: Solid 3/16" rods for beefier tone, longer sustain, easier bends, and smoother slides | Traditional guitar fretwire, wide | Traditional guitar fretwire, wide | Pepperoni-Tone® frets: Solid 3/16" rods for beefier tone, longer sustain, easier bends, and smoother slides |
| Fret Material | Specially-Designed Metal Alloy | 18% Nickel-Silver | 18% Nickel-Silver | Specially-Designed Metal Alloy |
| Pickups/ Saddles | Guitar Saddles with standarrd piezo orientation | Guitar Saddles with standarrd piezo orientation | Guitar Saddles with standarrd piezo orientation | Custom M5 Saddles with piezo crystals rotated for tapping |
| Marker Board | Removable and Replaceable | Permanent | Permanent | Permanent |
| Audio Outputs | 1 Output | 1 Output | 2 Outputs (8 bass strings, 16 treble strings) | 2 Outputs (8 bass strings, 14 treble strings) |
| Audio Output Jack | (1) Female 1/4" Mono Jack | (1) Female 1/4" Mono Jack | (1) Female 1/4" TRS Jack | (1) Female 1/4" TRS Jack |
| Control Knobs | Left Knob: Master Volume | Left Knob: Master Volume | Left Knob: Master Volume, | Custom teardrop knobs with tactile and visual indication. Tone filter voiced warmer than previous generations |
| Standard Accent Plates | N/a | Gloss Black | Gloss Black | Glossy hand painted tortoise with deep embedded logos. (features all new updated logos) |
| String Terminals | Quick-screw clamps, no winding necessary, no slipping or detuning | Quick-screw clamps, no winding necessary, no slipping or detuning | Quick-screw clamps, no winding necessary, no slipping or detuning | Quick-screw clamps, no winding necessary, no slipping or detuning |
| String Tuners | Easy front access with small hex-drive screwheads to prevent accidentally bumping out-of-tune | Easy front access with small hex-drive screwheads to prevent accidentally bumping out-of-tune | Easy front access with small hex-drive screwheads to prevent accidentally bumping out-of-tune | Easy front access with small hex-drive screwheads to prevent accidentally bumping out-of-tune |
| Action | Fully adjustable at both ends of string | Fully adjustable at both ends of string | Fully adjustable at both ends of string | Fully adjustable at both ends of the string, Player end adjustable on top side (easier). |
| Intonation | Fully adjustable intonation screws with anti-vibration dampers for safe transport | Fully adjustable intonation screws with anti-vibration dampers for safe transport | Fully adjustable intonation screws with anti-vibration dampers for safe transport | Fully adjustable intonation screws with anti-vibration dampers for safe transport |
| Overall Body Dims (inches) | 28.960" x 8.440" x 2" | 32.171" x 10.250" x 2" | 38.520" x 13.500" x 2" | 36.750" x 13.800" x 2" |
| Instrument Weight (w/o case) | 10.5 lbs (birch) | 11.5 lbs (birch) | 19.5 lbs (birch) | 22.5 lbs (birch) |