Transformer Buddy

Res ipsa loquitur.

But in the case the music's too loud to hear anything, here's what it says on the website:

Transformer Buddy™

Plug-in big transformers without blocking other outlets

Transformer Buddy adapters make sure one transformer takes up only one outlet on a wall or power strip.

Also works as a 104-Joules surge suppressor; has an LED "Protected" indicator.

Each grounded adapter rotates 360° to make room for other plugs.

15-amp, 1875-watt capacity.

1-1/2" x 3-1/8" x 1" thick.

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Two for $9.99.