This item has different variations.

Jammers are machine blocks which help world owners to block several things they don't want.

There are 4 main kinds of them:

Items What it does
ItemSprites.png Signal Jammer Prevents the world from showing up in the world menu, and changes the world name in broadcasts into JAMMED!.
ItemSprites.png Punch Jammer Prevents visitors from pushing and pulling each other by punching around.
ItemSprites.png Zombie Jammer Prevents infected visitors from infecting others in the world.
ItemSprites.png Balloon Jammer Prevents players from throwing War Balloons in the world.

There are also several other items which act like a jammer, but don't have the looks of one:

Items What it does
ItemSprites.png Ghost Charm Prevents ghosts from spawning in the world.
ItemSprites.png Guardian Pineapple Prevents consumables to be used in the world; was added to prevent people from exploding pineapple growtopians in the world.
ItemSprites.png Firehouse Prevents fires from spreading by instantly putting them out
ItemSprites.png Mini-Mod Prevents people from dropping items in the world.
ItemSprites.png Xenonite Crystal Blocking/granting Mods that the owner wants
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