DS Time Radar
From the Super Mario Wiki
The DS Time Radar is a machine invented by Professor E. Gadd which appears in the game Mario & Luigi: Partners in Time. It is first used after defeating Junior Shrooboid, where E. Gadd uses it to find out in what time period and where Princess Peach was. It reveals she was stuck in the past of the Mushroom Kingdom. The DS Time Radar was also used to activate the Hydrogush 4000 later in the game.