The 4-40 Bolt-On Swivel Ball Links may be used with Airplanes or Cars. INCLUDES: Four Socket screws (4-40 x 1/2) Four Hex shanks/w ball swivel (nylon with brass) Four Standoffs (brass) Four Hex nuts (4-40) FEATURES: The hex shaped shank helps the swivel arm thread on smoothly and hold tightly without additional hardware. The brass swivel allows the control arm to move freely through a wide range of motion. The socket screws and hex nut are zinc plated and hold tightly in place to provide a strong center pivot. Accepts a 4-40 threaded rod.REQUIRES: 3/32 hex wrench to tighten screw GPMR8002.