Our reservoirs come in 3 types for you to choose from based on your insulin needs. They are uniquely designed with a specific MiniMed™ connection, for a more secure insulin delivery. It is recommended to change your MiniMedâ„¢ reservoir every 2 to 3 days and Extended reservoir every 7 days. If your Total Daily Dose of Insulin (Basal insulin plus typical meal time Bolus insulin) is less than 48 units you may want to consider using the 1.8ml MiniMed™ Reservoir (MMT-326A) instead of 3ml MiniMedâ„¢ Reservoir. The 1.8ml Reservoir is suitable for all sizes and types of MiniMed™ Insulin pump systems. Extended reservoir can only be used with Medtronic Extended infusion sets.