This is a motor mount designed to be used with a square tube (or bar) arm. It provides a number of mounting holes for both motor can the reach arm, including a recess for the wires coming out of the motor (originally designed for a bell style motor). The mount has been engineered to fail when a crash occurs (but only when a crash occurs) to help maintain the condition of more expensive quad parts (so far all tests are successful with the mounts failing when required).Just simply print this little fella off and attach him to a quadcopter, use screws or cable ties to attach your motor and your good to go!