We design in the extra cups and power to compensate for the loss of vacuum at altitude. Here is a chart to show the effects and keep in mind if traveling at severe altitude. The mini-bomber by example has 4 cups that test at over 210 pounds (we have a safety factor built into this number as well) per cup x 4 = 840#’s The worst case scenario at 15,000′ leaves the power at 473 pounds. You can 1/2 that again and you have your double+ safety factor. These are vacuum cups, not suction cups! Remember there is always the indicator band that tells you how much power is in the cups.