Implementation of breach detection systems (BDS) can be a complex process with multiple factors affecting the overall Security Effectiveness of the solution. The following factors should be considered over the course of the useful life of the solution: Detection rate, anti-evasion capabilities (resistance to common evasion techniques), device stability and reliability, and time to detect. In order to determine the relative Security Effectiveness of devices on the market and facilitate accurate product comparisons, NSS Labs has developed a unique metric: Security Effectiveness. By focusing on overall Security Effectiveness instead of the detection rate alone, NSS is able to factor in the ease with which defenses can be bypassed, as well as the reliability of the device. This report is part of a series of Comparative Reports on security, performance, total cost of ownership (TCO), and Security Value Map (SVM). In addition, a SVM Toolkit is available to NSS clients that allows for the incorporation of organization-specific costs and requirements to create a completely customized SVM.