Inside diameter : 2 inches (50 mm) Outside diameter: 2-1/2" (64 mm) Pack of 2 O-rings. Made of zinc alloy metal with rust-preventive coating. High strength and high resistant to corrosion. Spring-opening O rings for key ring, purse loops, handbag, diy craft projects and more. More metal craft accessories for your creations, please visit our CRAFTMEMORE storefront on Amazon! Spring-opening O rings for key ring, purse loops, handbag, diy craft projects and more.