Spray foam sealant cylinders are two-component sealants that require a constant pressure dispensing system (CPDS) to fill gaps around doors, windows, ductwork, and plumbing fixtures. The insulation effectiveness of the sealant is measured by an R-value which is based on the density and cell structure of the foam. The higher the R-value, the more effective the insulation. With the required CPDS system (not included) they provide more coverage than standard spray cans or kits.