Features1-3/4 x 4 in base is ideal for use where mounting area is limited such as on skylight frames or narrow extruded shapesTwo mounting holes are provided for secure mounting using machine or self tapping screwAt least two mounting holes that will accept a 10 to 24 AWG or larger bolt or screw shall be provided in the support so that it can be permanently and rigidly fastenedNarrow internally threaded hub baseA threaded hub provided for the attachment of the air terminal shall have at least five full threads and if internally threaded, shall have a wall thickness of not less than 1/16 in (1.6 mm) measured at the base of the threads