High quality 316L surgical stainless steel ball closure ring (BCR). The ring features a clip-in skull measuring 5.5mm x 8.5mm. Underneath the skull there is a single handcuff with an outer diameter of 6mm. The sides of the skull each feature a small indentation which enable the skull to be held in place by way of a tension grip. To remove the clip-in skull,l pull the two ends of the ring apart and the skull will drop out. To replace the skull, pull the two ends of the ring apart, position the two dents on either side of the skull onto the ring ends and then release your hold on the ring. The two ends of the ring will squeeze together to hold the skull in place. This steel ball closure ring (also known as a captive bead ring) is available in a choice of 1.2mm and 1.6mm gauge, along with a choice of internal diameter sizes between 10mm and 16mm.