B539DDX Sealed Extra Light Torque Tube Type Airframe Control Bearing 3/4" x 1-7/8" x 9/32"B539DDX Airframe Control Bearing Sealed 3 4" x 1 7 8" x 9 32" Extra Light Torque Tube Style Non Aircraft Use The B539DDX is an extra light duty airframe control bearing built for smooth operation in demanding mechanical systems not certified for flight use. This sealed, full complement bearing features 24 balls and is made from high carbon chromium alloy steel. Ideal for control linkages, motion systems, and equipment requiring low rotational