Panel Fit Windows PANEL FIT WINDOWS FIN have developed a panel fit range of windows specifically designed for use with 50mm and 75mm insulated panels such as found in caravan annexes, house boats and demountable buildings. These windows have a 20mm channel all around and simply push onto the wall during construction. This method of construction also uses the face fixed range of doors. Key Benefits of Panel Fit Windows Makes construction a breeze Ask about Panel Fit Windows Full NameEmail* Phone*CompanyMessageNameThis field is for validation purposes and should be left unchanged. This iframe contains the logic required to handle Ajax powered Gravity Forms.