Nipple shield
From Voyeurweb's Wiki about Sex
Nipple shields are a type of nipple jewelry attached to her nipples turning them into pierced nipples. Nipple shield usually consist of a nipple bar going through her nipple and a conical shield encircling her nipple and covering parts of or the entire areola. The intent of wearing nipple shields is to ornament her nipple. Wearing nipple shields might stimulate her nipples.
Nipple shields can be made out of latex, silicone or metal.

