Koopascope

The Koopascope is a special periscope-type device that was created by Kooky von Koopa. It is used to see through Warp Pipes.

In The Adventures of Super Mario Bros. 3 episode "Oh, Brother!", Kooky uses the Koopascope to spy on Mario and Luigi in the Mushroom Kingdom from an underground dungeon. By simply inserting the Koopascope into a Warp Pipe, Kooky is able to monitor Mario and Luigi on the other end of a network of pipes.

The Koopascope was clearly designed for capturing purposes, as one can view their target through the Koopascope with crosshairs.