The term "Mechanism Shielded" is not a standard feature for the Hospira Plum A+; instead, it likely refers to the pump's cassette-based design that shields the fluid pathway from the outside environment, ensuring a closed system during delivery. The pump is a volumetric infusion system that uses a cassette and delivers multiple therapies concurrently through its unique PlumSet technology. Key features include automated back priming to prevent air exposure and hazardous drug exposure, air-in-line detection, and compatibility with Hospira's MedNet software for enhanced safety and drug management.