Shutters (known as Metal Poles in Super Metroid) are a type of mid-room barrier that appear in Super Metroid, Metroid Fusion and Metroid: Zero Mission. They block progress (usually directly in front of a door or hall) until an upgrade or path around them is found. If Samus has the Wave Beam, it will penetrate the barrier and can open it from the "wrong side".
In Super Metroid, there is also one special type of shutter. Green lighted shutters indicate a Super Missile. Also in Super Metroid, when Samus acquires the Hyper Beam, she can destroy shutters with one shot.
In Metroid: Zero Mission, they appear throughout Chozodia and the Space Pirate Mothership, blocking Zero Suit Samus' way. They cannot be lifted by Samus. Instead, she must wait for the Space Pirates to lose sight of her, at which point they will automatically open.
"There are several metal poles in the passages of Zebes. The color of the lights above these poles should give you an idea on how to make them move out of the way."
"Shutters can be opened by shooting the lamps with beams."
- There is a glitch in Super Metroid commonly known as the "Green Gate Glitch", where Samus must run up to a green-lighted shutter, jump and shoot diagonally at a certain spot to open it the wrong way. This is used in many instances, such as getting the Screw Attack early. However, this glitch only works on gates with left-facing lights.
- A sort of shutter appears in Metroid: Other M during the final Countdown sequence, though they are gates instead of poles. They appear in two hallways and are consistently closing. Zero Suit Samus is required to slide under them, but if she cannot make it, she can fire a charged shot of the Paralyzer or multiple uncharged shots.
- Interestingly, red-lighted shutters and yellow-lighted shutters appear in the data of Super Metroid, accessible via the Super Metroid Integrated Level Editor (SMILE). However, neither of these two shutter variants are actually encountered in the game.