Pregnancy Maternity Flexible Surface Piercing Belly Button Ring Stainless Steel Balls Threaded Retainer - Nickel / Allergy Free - 14G Stainless steel twist ball ends 14G. Surgical Grade. Comfortable fit, Nickel Free, Allergy Free Flexible retainer that can be cut to any length. If you need to resize, cut at an angle for best results. This type of retainer is the #1 Pregnancy belly ring retainer Autoclavable, flexible, comfortable - choose your pre-cut size.