Slit to Agar Air Sampler source?

[Michael Betlach]

I'm interested in using a slit to agar air sampler to monitor airborne 
bacteria for periods of 30 minutes or longer rather than collect discrete 
samples periodically with a centrifugal sampler (RCS Biotest) or SAS 
unit.  I'm especially interested in one that accepts 100 mm diameter 
petri plates. Does anyone have the address for a current supplier of 
slit-to-agar units? Thanks much for your help.

Michael Betlach