Looking for a variable speed switch for air circulation fans

[japollon]

I've installed two Attwood Turbo 3000 in-line blower fans to circulate air to the foot boxes. They are a single speed fan and I would like to add a variable speed switch to control the flow. The fans each draw 3.1 amps. Can anyone suggest a simple switch to support this function?

Thanks

[GoDadGo]

Could this do the trick?

Cole Hersee Rotary Switch - 7493-BX

Just search it and you will find several vendors who sell it.