Trustmark 14K Yellow Gold in Silicone Padded Replacement Backs for Post Earrings Mushroom Shape One pair or set of replacement backs (2 pieces) for earrings with friction-back posts. Made using a Solid 14K Yellow Gold friction back encased in a Silicone pad. Silicone exterior improves holding strength to reduce the chance of the back falling off. Style or Setting: Backing for friction-back post earrings for pierced ears. Hole Size: 0.89mm | 0.035 inches, overall width of 5mm including Silicone. Fits most standard friction back posts. The opening may be too large for thin post earrings (those thinner than the standard size or thickness).