Ultrasonic Insert, 1/4"-28, 19/64 in L, 0.363 in Insert Dia., 0.349 in Tapered End Dia., BrassMfr #: TH 428 SV PK50 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.