Inline MDI Adaptor for Dosage Counters. 22 mm I.D. Inlet x 15 mm I.D./ 22 mm O.D. outlet. Single-patient-use adult metered dose inhaler (MDI) adapter ensures safe and complete delivery of prescribed aerosol medication. Adapter remains inline to help reduce cross-contamination and improve patient comfort by reducing manipulation of circuitArrows clearly mark the direction of flow; built-in tethered plug can be used to seal the breathing circuit when no MDI canister is in place. Compatible with both plastic and metal canister stems. Can be used with or without dosage counter.