A device for joining a plastic part to a second part with an insert adapted to thread into the plastic part. The insert includes a longitudinal body with outer threads, a hole in the longitudinal body with female threads, and an annular flange. Protrusions and recesses on the bottom of the annular flange alternate in a radial pattern. The insert is threaded into an opening in the plastic part. The protrusions and recesses of the insert interact with the plastic part to resist over rotation of the insert. The opening in the plastic part may include a hole and a counter bore portion. The counter bore includes protrusions and recesses. The protrusions and recesses alternate in a radial pattern. When the insert is threaded into the opening, the protrusions and recesses of the insert interact with the protrusions and recesses of the plastic part and resist over rotation.