The VELUX Insulation Collar with Underfelt Collar 78 X 98cm is an exceptional product designed to ensure a weather-tight seal between your roof window and the roofing material. With its innovative design, this insulation collar helps to enhance the thermal efficiency of your roof window, reducing heat loss and preventing condensation. The underfelt collar also guarantees a tight seal and ensures easy installation of your roof window. Its an essential component for any VELUX roof window installation, providing you with peace of mind knowing that your home is well protected from external factors.