Hammer Suit

"Hey you! How about lending me your clothes? No dice!? What a drag!"

- Kings

The Hammer Suit (alternatively Hammer Bros. Suit,  Hammer Brothers Suit, or Hammer Brother Suit ) is an item found in Super Mario Bros. 3 and Super Mario Advance 4: Super Mario Bros. 3. This item transforms Mario or Luigi into Hammer Mario or Hammer Luigi, which gives them the ability to throw hammers.

Super Mario Bros. 3 / Super Mario Advance 4: Super Mario Bros. 3
Hammers thrown by Hammer Mario or Hammer Luigi can defeat almost everything, including Bowser, but like all the suits, one hit from an enemy causes them to lose their power. The characters also gain a fireball-proof shell when ducking, but lose their ability to slide down hills. If Mario or Luigi ducks while in the Hammer Suit, they resemble a Buzzy Beetle.

In the original Super Mario Bros. 3, retrieving a Hammer Suit will make Mario and Luigi's skin turn a darker, yellowish tone, while no other power-ups in the game do so. It is unknown what purpose this skin color change has, but it is possible that Nintendo placed the odd effect in to make the textures of Mario and Luigi's skin bear more resemblance to that of the Koopa Troopas and Hammer Brothers themselves. In remakes, Mario and Luigi's skin color stay the same when they wear the suit.

Super Mario Maker / Super Mario Maker for Nintendo 3DS
In Super Mario Maker and Super Mario Maker for Nintendo 3DS, knocking on a Warp Door in the Super Mario Bros. 3 theme in Edit Mode may cause Weird Mario to appear in a Hammer Suit.

Trivia

 * The Hammer Suit (as well as Hammer Mario) is not mentioned in the original NES or All-Stars versions' instruction booklets. The Virtual Console re-release's Operations Guide, which is based on them, also has no reference to it.