Looking for a stirrer for Sf21 cell culture

[slhmm at cc.usu.edu]

Hi!  
I am looking for a slow-speed magnetic stirre for insect Sf21 cell culture.
I expect the stirrer having the function to control and display the speed
between 10-100 rpm.  The generation of heat on the stirrer should be as less
as possible.  At least six (6) spinner flasks can be run at the same time.
A stirrer can run nine (9) flasks is preferred.  Any related information
is welcome.  I am going to order one within a week.  Thank you very much.
Jeff