Do these earring backs have any allergies to the ears?

The earring backs were made of high quality silicone and a thin piece of 14K solid gold. Nickel free and hypoallergenic earring backings for sensitive skin.

How many pairs are in the package?

1 Pair. But the quality of the earring backs are well made and comfortable for wearing.

Are they snug enough so they won't slide off posts?

They are snug enough, but that will depend on the size of the earrings. Perfect for gauge of 20g thin post earrings, also could be used for screw stud earrings.

Will these work with screw back studs?

These work great for my screw back pair of Earrings. I ordered these because the original screw on backs that came with my earrings were difficult to put on and take off.(Customer's Review)

How big are these earring backs?

There is a 14K gold tiny little butterfly clip inside the half of the 4mm*6mm silicon ball. Weight of 0.16g/pair. Lightweight and comfortable.