Outside diameter: 8 mm [0.3 inch] , inside diameter: 6 mm [0.2 inch], thickness: 1 mm [19 gauge] Outside diameter: 10 mm [0.4 inch] , inside diameter: 8 mm [0.3 inch] , thickness: 1 mm [19 gauge] Note: to open the piercing, bend the hoop sideways as explained on the photo (otherwise it will lose its shape). This piece is used as a helix, tragus and daith piercing and it's not suitable for daily opening/closing. Note that this piercing is sold by piece not by pair How to treat your jewelry: About