Ultrasonic Insert, 3/8"-16, 5/8 in L, 0.54 in Insert Dia., 0.488 in Tapered End Dia., Brass, 25 PKMfr #: DV 316 TH PK25 THREADED INSERTS FOR PLASTIC E Z Sonic ultrasonic thread inserts for plastic are designed for post molding installation in thermoplastic materials. EASY INSTALLATION Install these metal threaded inserts ultrasonically or with a heat driver. The tapered design simplifies installation. FOR USE WITH APPLICATIONS The threaded inserts for plastic are designed for putting standard machine threads in 3D printed and thermoplastic parts.