The Supply Closet is a location in the Five Nights at Freddy's SMBX series.
This room can only be reached via the West Hall, where it can be visited via a wooden doorway. In the West Hall itself, the outer walls of the room is decorated by tiles and a window can be found above the doorway. The top tiles end in a wooden bar, which also features one of the secret orbs. (namely the West Hall's one)
The Supply Closet is the smallest room in Freddy's Pizza. It features features a wooden floor and a large closet made of wooden logs, which houses a rack with two brooms and is decorated with two large lighting contraptions hanging from the ceiling, with the right one featuring a light bulb while the left one is empty. There's also a small platform with a security camera mounted onto it, that is used by Mike Schmidt to monitor any animatronics moving around the Supply Closet.
Above the ceiling is a vent system, that holds one of the secret orbs, which can be reached by making clever use of the securtiy camera's platform as a stepping stone. Note, that due to his limited jumping height and necessary run-up, it is impossible for Foxy to reach this secret orb.
Note, that these tracks came with Super Mario Brothers X and the creator of FNAF SMBX takes no credit for the music in this game. All credit for the ingame music goes to Nintendo.
The Supply Closet shares its overworld track with the Backstage.
Despite featuring a vent system, only the area housing the secret orb is accessible. Unlike the upcoming FNAF SMBX 2 and 3, the first game doesn't allow the player to enter vents to jumpscare the night guard, as this would cause it to drift away from being faithful to the original FNAF.