Cisco C3900-SPE250/K9

C3900-SPE250/K9 is the Cisco Services Performance Engine 250 for Cisco 3945E ISR.
The Cisco 3900 Series offers field-replaceable Cisco Services
Performance Engine (SPE). These SPEs allow you to protect your initial investment in the Cisco 3900 platform for a longer time period and scale
router performance as your network and branch-office needs grow.