These single flare black bullet holes aremade from hand blown soda lime glass by gorilla glass. Size availability is limited by the availability of raw material (glass tubing). These are only available in the specific sizes we have listed here. They have a wearable area of approximately 3/8″ between the flare and o-ring. These don’t have a groove for the o-ring. Two clear silicone o-rings are included. Choose your size below.