RYMAX Fireproof Door Core Board | Fireproof Filling | Fire proof Board RYMAX Fireproof Door Core Board is a penetration of traditional products, it's developed specially for the requirements of Wooden Fireproof Door, Steel Fireproof Door with new special formula. It's more pertinency and superiority to the products due to the improvements on fireproof, plainness, strength, dryness and waterproof properties. Tested under China standard GB/T20285-2006, safety class of RYMAX Fireproof Door Core Board is Grade ZA2, and tested under GB/T8624-2006, fireproof class of RYMAX Fireproof Door Core Board is Grade A1 (highest grade). Properties: No deformation, crack, shrink under high temperature burning and high strength; it can double the fireproof time than common fiberglass magnesium board, it's the ideal filling material for all kinds of fireproof doors, such as wooden fireproof door, steel fireproof door, etc.