Titanium single flare plugs with a clear silicone O-ring by Stretch It Body Jewellery. Each size goes up by 0.5mm increments for a pain-free stretch. 
 
1mm - 5mm Kit contains one of each size:  1mm, 1.6mm, 2mm, 2.4mm, 3mm, 3.5mm, 4mm, 4.5mm & 5mm.
5.5mm - 10mm Kit contains one of each size: 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm & 10mm.