Straight barbell Plastic (+ 2x Balls) Retainer: suitable for medical scans and MRI's Externally threaded Designed for use in body piercing. 1.6 mm = 14G Straight barbell Attachments screw in to post. Non-Sterile Externally threaded Fits basic externally threaded attachments for 1.6mm = 14G barbells (non USA)