Explorer.

Root

Quality

Voicing

All G7 shell positions across the neck

Chord

Dominant 7 · Strings 6-4-3

Rb73

Tritone Substitution

G7 can be substituted with C#7 — a tritone (6 semitones) away. They share the same guide tones (3rd and b7), just swapped.

C#7str 6-4-3

Dom7 — Root on 6