This Gold coloured ball is made from top quality implant grade Titanium which has had a Gold PVD coating applied to make it hypoallergenic which means it is ideally suited for body jewellery use. It is compatible with 1.6mm (14 Gauge) externally threaded jewellery such as labret studs, barbells, belly bars and tongue bars. You can select 4mm, 5mm, 6mm or 8mm ball sizes, to give you some idea if you unsure 4mm is the ball size that is usually on a 1.6mm labret, 5mm is the standard top ball size for a belly bar or tongue bar and 8mm is the standard size for the bottom ball of a belly bar. 6mm balls are also popular with some people that prefer slightly larger balls on their tongue bars, labret studs or nipple barbells.