Cisco ASA5500-SC-20-50= software license/upgrade

-Enables creation of multiple security contexts (virtual firewalls) within a single Cisco ASA 5500 Series appliance, with each context having its own set of security policies, logical interfaces, and administrative domains.
-Supports four licensed levels of security contexts: 5, 10, 20, and 50 (the maximum number of contexts supported is based on the Cisco ASA 5500 Series model).
-Provides businesses a convenient way of consolidating multiple firewalls into a single physical appliance or failover pair, while retaining the ability to separately manage each of these virtual instances.
-Enables service providers to deliver resilient multi-tenant firewall services with a pair of redundant appliances.

Security Context Licenses
The Cisco ASA 5520 and 5540 can support up to 10 and 50 security contexts, respectively, where each context has its own separate security policies and administrative domain. These appliances include two contexts by default, and those contexts can be used for either Active/Active high availability or virtual firewall services. Several tiers of security context licenses are available, including 5, 10, 20, and 50 security contexts. This license type and related feature set are not supported on the Cisco ASA 5510.