Kay-Cel is a rigid, closed-cell, high-density polyurethane foam core panel. The reinforced panel is a sandwich construction with fiberglass reinforcements. The sheets have a 25lb density with 18oz Woven Roving on Both sides. Great for transoms, and other structural projects. 

ADVANTAGES: 

Excellent Strength-to-Weight ratio

Foam Reinforced with fiberglass increases mechanical properties

Lightweight - 30% Lighter Than Marine Plywood

Closed Cell Cross-Linked Polymer Foam will not absorb water

Will Not Rot...Excellent Replacement for Wood