C2951-universalk9-mz.spa.157-3.m8.bin !new!

Here is a short story about a night when this specific string of characters saved the day. The Ghost in the Rack

: Refers to the "Universal" image type. It contains all software features (Security, Unified Communications, Data) in a single package. The k9 indicates it includes strong "Payload Cryptography" (encryption), which is subject to export controls.