The Type-4 shuttlecraft (also known as the Class G shuttlecraft) was a shuttle design used by the Federation. The Type-4 shuttlecraft was used in the 23rd and 24th centuries.
This model of shuttle was functionally identical to the Class F shuttlecraft, with many cosmetic differences. Ships of this type entered service in the year 2269 on a provisional basis. One of the early models of this type of shuttle underwent test-flight piloted by Lieutenants Hikaru Sulu and Pavel Chekov in that year, while on leave from the USS Enterprise. (Decipher RPG module: Starships; TOS movie, novelization & comic adaptation: The Final Frontier; TNG movie: Generations; TOS - Unlimited comic: "Trekkers")
The designation "Class G" is from Decipher's Starships book, while "Type-4" derives from the comic "Trekkers"