The Gold used in this Piece is Totally Nickel Free, and available in either; solid 14K Yellow or White Gold.
This piece is used in many different piercings including but not limited to the navel, nipple, ears, and genitals.
The standard ball sizes used are as follows;

18-gauge includes 1/8" Balls
16-gauge includes 5/32" Balls
14-gauge includes 3/16" Balls
12-gauge includes 3/16" Balls

Other Gauges and Bead Sizes Available by Request