For standard duty interior floors.For mean joint sizes of min. 20 mm (3/4-inches), max. 25mm (1-inches)at mid-point of expected service temperature range FN 20/12 Surface Mounted, Flush Insert FKN 20/12 Surface Mounted, 3mm (1/8-inch) Raised Insert FTN 20/12 Surface Mounted, 5mm (1/4-inch) Raised Insert E-4 Surface Mounted, Floor-To-Wall option available for FN, FTN and FTN 20/12