Check the listing for details. 50 Pcs Comfort Impenetrable Soft Safety Backs, Secure Clear Rubber Earring Ba.... Condition: New. Listed at 12.70 USD. Safe Material: Our secure earring backs are made of high quality rubber material, which is safe, non-toxic, soft and comfortable, and not easy to cause allergies. Unique Design: These rubber earring backs have a practical spherical design, through which the studs cannot penetrate, preventing losing earrings or piercing earlobes.