The RG421 features a mahogany body bolted to a maple Wizard III neck with a 24-fret rosewood fretboard with white dot position markers. Components include Ibanez pickups and a fixed bridge. An update for 2015 introduced new pickups and a one-piece neck. For 2018 the rosewood fretboard was replaced with jatoba. For 2019 the mahogany body was replaced with meranti. For 2020 the bridge was replaced with the F106.