The IMPROVE sampler consists of four sampling modules operated by a single controller.  Many are housed in open-air stands, such as the unit shown in the photo below, at Capitol Reef National Park, Utah.  Others are housed in enclosed shelters.

The Site Operators SOP #201 contains operating procedures and a troubleshooting guide for the IMPROVE Sampler.  This SOP also includes photos and diagrams of the sampler and of the sampler cassettes.