The unit $BTU_{IT}$, Inch per Square Foot Second Degree Fahrenheit, is an Imperial unit for 'Thermal Conductivity' expressed as $Btu_{it}-in/(ft^{2}-s-degF)$.
British thermal unit (international table) inch per second Square foot degree Fahrenheit is the unit of the thermal conductivity according to the Imperial system of units.
British Thermal Unit (international Definition) Inch per Square Foot Second Degree Fahrenheit