The best window door & siding sealant OSI offers QUAD MAX is flexible with 5x stretch and Class 50 Joint Movement capability so you have zero reasons to worry about a job once youÆve done it right the first time. Designed for sealing around exterior/interior windows doors and siding QUAD MAX bonds to a wide variety of Primary Window Door and Siding Building materials such as fiber cement cedar brick stone coated aluminum fiberglass vinyl PVC stucco EIFS wood glass and flashing tapes and Kynar coatings.