PR-1428 Class B is a low tack sealant. It has a service temperature range from -65 ° F (-54 ° C) to 250 ° F (121 ° C) with intermittent trips up to 135 ° C (250 ° F). The material is designed for use as an access door sealant or in the fabrication of form-in-place (FIP) seals. It can also be used to protect electrical wiring, terminals and equipment against fuel moisture, dirt, and short circuits.

PR-1428 Class B is a two part, manganese dioxide cured, polysulfide compound. Uncured material is a low sag, thixotropic putty suitable for application by extrusion gun or spatula. It cures at room temperature to form a removable seal to common aircraft substrates.