Black Heavy Gauge Thick BCR Ring - Spring Loaded Ball
Heavy gauge ball closure ring.
This ring is surgical steel, and is available in 3mm, 4mm, 5mm, 6mm, 8mm and 10mm thicknesses.
The bar length is the internal diameter of the ring. You do not measure the outside as this is not considered the wearable area.
The spring loaded ball means these can be opened by hand.