What is not a feature of a Spill-Resistant Vacuum Breaker?

A Spill-Resistant Vacuum Breaker is designed to prevent backflow in irrigation systems, particularly in scenarios where there is a potential for siphoning. One of the characteristics of these devices is that they can handle fluctuating pressures in the irrigation system effectively.

The choice stating that it is "Good for constant pressure" reflects a misunderstanding of the functionality of a Spill-Resistant Vacuum Breaker. While these devices can manage pressure changes, they are primarily intended for protection against back siphonage, not specifically for maintaining constant pressure. The design includes features that allow for drainage and proper function under varying conditions, but stability in pressure is not a defining feature of its operation.

The other options represent standard and critical features of Spill-Resistant Vacuum Breakers. They must be installed at a height of at least 12 inches above the highest outlet to ensure proper function. Having two shut-off mechanisms contributes to the reliability and effectiveness of backflow prevention. Additionally, the inclusion of one test cock is necessary for maintaining the system and ensuring that the device remains operational and effective at preventing backflow.