PREGNANT Belly Button Ring. Flexible Pregnancy Belly Button Ring. Body Jewelry for pregnancy. Keep your piercing intact with this flexible pregnancy PTFE belly ring. The adjustable length pregnancy barbell will allow you adjust the piercing to your size. Specifications: Flexible Self Threading 14 Gauge (1.6mm) PTFE Shaft, 2" Length, and FOUR (4) Acrylic UV 6mm Balls. DIRECTIONS: Cut the 2" shaft to your desired specifications. This acrylic flexible shaft is SELF-THREADING. The barbell will be threaded when the ball endings are screwed onto the straight barbell for the first time.