We are the FIRST to offer this solution, with your comfort top of mind! The FLAT backing is easily removable so you can change your earrings as you wish. The short, adjustable post means no poke and secure sleep-in comfort. This three prong 'martini' setting for maximum sparkle. Back-Off studs have a SHORT POST with two adjustable lengths (5mm and 6.5mm) Sold as a single. Small 0.06 ct / Medium 0.12 ct / Large 0.25 ct / ExLarge 0.50 ct / Bling 1.0 c Dimensions: Small = .12" diameter (3mm). Medium = .15" (3.75mm) Thoughtfully designed for sensitive ears using hypoallergenic, nickel-free materials.