For our 1st collection of key rings, we wanted to pull from some of our most popular pieces. These skulls are hand cast from traditional bone carved Tibetan skulls which are a positive reinforcement of life. Skulls are 3/8" (1 cm) and 1/2" (1.3 cm) in length. We've teamed 2 of them with this classic flat wire split ring (1" round). All in aged sterling silver.