This monitor is suited for compounds for which activated carbon shows limited capacity. Accuracy of +/-25% at a 95% confidence level for many workplace contaminants. Bulk packed. Analysis not included. The 3M™ Organic Vapor Monitor 3520, with Backup Section uses the proven scientific principle of diffusion, which is the gradual mixing of molecules of two or more substances. Primary and back-up sorbent pads are included for sampling demanding environ