Unibond expanding foam 500 mlthis 500ml expanding foam from unibond has been specially designed for filling sealing and insulating most building materials simply apply and leave for 12 hours to dry it comes in an easily storable and transportable aerosol and expands to the exact size of the cavity you need filling if youre using it during redecoration projects its sandable and paintable making it perfect for giving a smooth professional finish once dried