The YouTube channel Boundary Break usually checks out what goes on out of bounds in video games, but their latest video breaks down some of Nintendo’s most well-known hardware to show secret messages and exactly what made your Zapper sound so weird.

I’m not much of a gearhead when it comes to consoles, although I’ve cracked carts and poked around at EPROMS before. Boundary Break host Shesez doesn’t just open cartridges to look at the boards but also picks apart Nintendo consoles and peripherals to show off some pretty interesting features.

Some of the more intriguing cross sections include the Nintendo 64 Rumble Pak—which is mostly a hunk of brass that spins whenever the circuit tells it—and the spring-triggered NES Zapper. It turns out that the trigger uses way more springs than I imagined, all to jury-rig a mechanism that allows it to make contact with a button hidden inside.

Busting controllers and consoles shows off some of the more playful touches in their construction. There’s a clear look at the Nintendo Switch Pro Controller’s hidden message reading “THX2ALLGAMEFANS,” and the strange mirror system used to send images through the Virtual Boy. It’s a fun chance to see how Nintendo engineers some of their most memorable gadgets.