Jackson and Charvel Unveil Sleep Token's First Signature Guitar and Bass

Jackson and Charvel unveiled the first-ever Sleep Token signature instruments on August 26, 2026 (Premier Guitar): the Jackson Pro Plus Series Signature Sleep Token IV Monarkh SC for guitarist IV, and the Charvel Sleep Token III Signature Pro-Mod San Dimas Bass V for bassist III. Both brands are owned by Fender Musical Instruments Corporation (FMIC), and both companies call it the first signature collaboration in the anonymous band's history.

Per Guitar World's own coverage, this isn't a guitar dreamed up in a boardroom: IV's existing touring rig already included a custom-shop, EverTune-equipped 30-inch single-cut baritone, and the new Monarkh SC is that same guitar brought to production.

Neither Jackson nor Guitar World names an exact pitch for IV's "whole-octave-down tuning," so don't trust any specific note-by-note breakdown you see elsewhere as confirmed. What is confirmed, directly from the spec sheet, is the hardware built to survive it: a 30-inch scale and an EverTune 6 bridge, a combination CYS has already mapped for exactly this territory.

CYS's own baritone string gauge chart covers the 30-inch scale directly. Ernie Ball's Baritone Slinky (.013-.072) is the set that chart calls "actually built for" true A standard and lower, the heaviest stock baritone option from either major manufacturer. D'Addario's EXL157 (.014-.068) is the long-scale alternative, though D'Addario's own chart calculates that gauge at B standard, a full step above where a "whole-octave-down" guitar likely lives. For a tuning this extreme, the heavier Ernie Ball set gives more usable tension before the low string turns to rubber. Guitarists chasing this tone on an existing baritone or 27-inch-plus guitar can start there rather than guessing at a custom gauge; CYS's baritone player guide has more documented rigs at comparable scale lengths for reference. For context on the next tuning rung up, CYS's Drop A guide covers the more common 7-string territory most players reach for before going this low.

III's new Charvel is a five-string Pro-Mod San Dimas with a resonant poplar body, a caramelized maple neck and fingerboard, and a 12-to-16-inch compound radius for comfortable low action across the neck. The standout spec is the 34.4-to-35.5-inch multi-scale, fanned-fret design, which spreads more tension across the low B string without sacrificing playability up top.

Multi-scale construction doesn't require special strings, a standard 5-string set installs and intonates normally once the bridge saddles are set. For a low-B 5-string in standard B-E-A-D-G, Ernie Ball's Power Slinky Cobalt 5-String (.050-.135) is the heaviest stock 5-string gauge in Ernie Ball's Cobalt lineup, with enough low-string mass to keep a 35-inch-plus B string from feeling loose.

Sleep Token performs entirely masked, cloaked, and anonymous, and per Guitar World, the band has become "one of the most talked about bands of our generation" in "as little as three albums," credited with "redefining contemporary heavy music with a sound that traverses cinematic pop, sultry hip-hop, crushing djent, smooth R&B, and everything in between." IV plays guitar and backing vocals; III plays bass. Neither player's real identity is publicly confirmed.

That anonymity is worth naming as a limit on this piece: CYS can confirm what Jackson, Charvel, and Guitar World have published about the instruments themselves, but nothing about IV or III beyond their on-stage roles. Treat any claim about who is actually behind the masks, on this page or anywhere else, as unconfirmed.

The Monarkh SC lists at $2,199.99 and the San Dimas Bass V at $1,599.99, both available now through Jackson and Charvel dealers. Neither product page lists Amazon availability as of publication, so factor dealer shipping and setup into the price if you're ordering one sight unseen. The bigger catch for players chasing IV's exact tone: without a published tuning or factory string gauge, you're extrapolating from the hardware spec, not copying a confirmed sheet the way you could with, say, a signature set that names its gauge outright.