MATERIAL: this earring backs locking made of stainless steel, tarnish free and lead-free, keep durable and non-allergenic.SERVICE PROMISE: please contact us if you have any problems with these secure earring backs for diamond studs.STYLE: locking earring backs is security, convenience and comfort with an internal spring lock to secure the back. this special lock design allows you to use these earring backs safety backs on valuable earrings safely and you could enjoy all the date and party and wont lost your expensive studs because these earring backs hold tight.ORDER INCLUDES: 6pcs earring backs silver and 24pcs silicone piercing disc earring lifters backs in total for one order. this earring backs safety backs is a best gift for yourself to prevent loss the valuable studs.SIZE: thickness: 20 gauge(0.8mm) or 19 gauge(0.9mm) would be better to fit this earring backs. please check your earrings post type and size to match perfectly before buying.