From the Super Mario Wiki
A Propeller Box is an orange block with eyes, and a yellow propeller. The player is able to wear it over their bodies. The blades of the propeller can be used to rapidly fly into the air to a great height, and then slowly fall back down towards the ground.
A Propeller Box is a power-up first seen in Super Mario 3D Land. The Propeller Box is lost once the player finishes a level, but an extra life is rewarded. While wearing a Propeller Box, Mario or Luigi can't throw boomerangs or fireballs, or turn into a statue, but they're still able to swing their tails. Both Mario and Luigi's Propeller Boxes stay orange when being worn.
Propeller Boxes also appear in the follow-up title Super Mario 3D World, where they act in a way similar to the predecessor, though now the box color depends on which character is wearing it. While Mario retains his orange box, Luigi now has a green one, Princess Peach has pink, Toad has blue, and Rosalina has cyan.
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