A One-Way Wall is an object which appears in Super Mario Maker, Super Mario Maker for Nintendo 3DS, and Super Mario Maker 2.
Description[]
One-Way Walls are designed so that if Mario passes through one, he cannot go back through it from the other side, much like the Flippers from the Yoshi's Island series series. In the Super Mario Maker series One-Way Walls are available to use in every style except the Super Mario 3D World style in Super Mario Maker 2. One-Way Walls are typically seen pointed to the right, but some instead point left, up, or down. One-Way Walls pointed upward can be used as a platform.