Each pair is laser cut and engraved from 1/8 inch acrylic and are waterproof however I'd recommend removing them before showering or swimming since the engraving is filled with paint that could potential wear off.
The earring posts and dangles are stainless steel and nickel free.
Measurements for Stud Earrings:
.499 inches wide and .445 inches high
*Due to the variation from cellphone or monitor screen color can be slightly different from the picture.