Here is a link to a more exact version of the one I have. Note its rated for 15 amps. Also even though it shows only 3 settings, its a dial, its got 100s of settings.

https://www.amazon.com/Casolly-Variable-Controller-Exhaust-Inline/dp/B07BMR4THQ/

Like I said in my post I basically wana do what people are doing with long extension cords, but with a speed control? I'm not looking for anything exact or precise.... just quick and trying to slow down my roast time slightly. I would even be happy with 5% slower.