The Nu-Calgon 4293-04 Nu-Foam Expanding and Insulating Sealant is an expanding, polyurethane, prepolymer foam that is used as a sealant and an insulating product. It is designed to seal, fill and insulate small cracks, gaps and voids. Tack free time for Nu-Foam is less than 30 minutes at 70°F and 40-50% relative humidity. Its R-Value is 4.9 per inch thick making a very good insulator in most any application and can even provide sound-deadening. Nu-Foam is UL classified and is fire retardant. Can withstand temperatures up to 240°F. It can be used to seal and insulate areas such as openings created for refrigeration, air conditioning and heating tubes or pipes, duct joints, utility penetrations in exterior sheeting, masonry, concrete or wood walls, and other areas where unwanted air penetration might occur. THE NU-CALGON 4293-04 NU-FOAM EXPANDING AND INSULATING SEALANT IS FOR PROFESSIONAL USE AND SHOULD ONLY BE USED IN ACCORDANCE WITH ALL REGULATIONS AND PROPER SERVICE PRACTICES. PLEASE SEE PRODUCT LABEL OR CONTACT NU-CALGON DIRECTLY FOR USE INSTRUCTION. IT IS RECOMMENDED TO UTILIZE THE APPROPRIETE PPE (PERSONAL PROTECTIVE EQUIPMENT) DURING APPLICATION.