[Note: potential subjects who cannot demonstrate successful MDI technique using with the AIM device (with placebo canister) after in-clinic training at the Screening Visit will not be eligible for continued participation in the study.] 12. At the Screening Visit, demonstrates adequate understanding of and ability to successfully inhale when using the Halix™ UDDI [Note: a placebo UDDI not containing any drug powder will be supplied for each potential subject to become familiar with the inhaler and practice inhalation technique] [Note: potential subjects who cannot demonstrate successful inhalation technique using the Halix™ UDDI after in-clinic training at the Screening Visit will not be eligible for continued participation in the study].