OXVA UNIpro RBA The UNIpro RBA Coil is compatible with the Velocity 21700 Kit from OXVA for DIY fun. The UNIpro RBA is the first MTL & DTL RBA and comes with an airflow control ring and an MTL reducer, bringing you a great and professional mouth-to-lung experience. Package Includes: 1 x UNIpro RBA Coil 1 x 1.5 MTL Airflow Reducer 1 x Airflow Ring 1 x 510 Drip Tip 2 x Accessories Bags