The C3900-SPE150/K9 is the Cisco Services Performance Engine 150 for Cisco 3945 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.
Cisco Services Ready Engine (SRE) modules are router blades for the second generation of Cisco Integrated Services Routers (ISR G2) that provide the capability to host Cisco, third-party, and custom applications. A service-ready deployment model enables branch-office applications to be provisioned remotely on the modules at any time.
Here are the product specifications for this model:

Processor: 1.5 GHz dual-core
DRAM: 2 GB
Flash Memory: 8 GB
USB 2.0 ports: 2
CompactFlash slot: 1
External USB ports: 1
Management port: 1
Ethernet ports: 4 (10/100/1000)
Security: Hardware-based encryption acceleration, onboard VPN acceleration, onboard SSL acceleration
Dimensions (H x W x D): 1.73 x 14.76 x 16.25 in. (4.39 x 37.49 x 41.28 cm)
Weight: 7.5 lb (3.4 kg)

Overall, the Cisco C3900-SPE150/K9 provides a high-performance and reliable solution for organizations requiring advanced routing and network services.