Finally, there is a reliable, easy-to-use and cost-effective device designed to accurately monitor MDI usage. The lightweight DOSER attaches easily to the top of the inhaler and is automatically activated to record each inhalation taken. The DOSER displays the number of inhalations remaining in the canister, and the number of inhalations taken each day. The DOSER also stores daily usage information for 30 days in its "history" memory. The DOSER does all of this without altering standard user techniques, and helps avoid the danger of a suddenly empty inhaler.