PR-1776M Class B is a low density, high temperature aircraft integrated fuel tank sealant. It has a service temperature range from -65 ° F (54 ° C) to 250 ° F (121 ° C), with very limited travel to 360 ° F (182 ° C). This material is designed for fillet sealing of fuel tanks and exposure to other long-term aircraft fuels to both jet fuel and aircraft gas and will resist limited contact with diphosphate ester-based hydraulic fluids.

PR-1776M Class B is a two component, manganese dioxide cured polysulfide modified with Permapol® P-5. Uncured material is a low sag, thixotropic putty suitable for application by extrusion gun or spatula. It cures at room temperature to form a flexible sealant with excellent adhesion to common aircraft surfaces.

The PR-1776M Class B is designed to be a direct replacement for the PR-1776 Class B.