Armstrong Design Envelope boosters address the water delivery challenges presented by high-rise buildings by combining high-efficiency Vertical Multistage pumps or dualArm pumps with modern variable speed controls. Armstrong Design Envelope solutions are sized using a pre-set collection of the most efficient booster sizes for a range of performance levels, so they can easily adapt to changes in design, site or operating conditions. Over the life of your building, the Design Envelope approach to selection protects you against potentially costly and time-consuming system rework.