Cisco 2921 Voice Sec. Bundle, PVDM3-32, UC&SEC Lic,FL-CUBE10 MEMGB= 2GB DRAM (1 DIMM) for Cisco 2901, 2911, 2921 ISR, Spare MEMGB= 1 GB DRAM (1 DIMM) for Cisco 2901, 2911, 2921 ISR, Spare MEMMB= 512MB DRAM (1 DIMM) for Cisco 2901, 2911, 2921 ISR, Spare MEMU1.5GB 512MB to 1.5GB DRAM Upgrade (1GB+512MB) for Cisco MEMU1GB 512MB to 1GB DRAM Upgrade (512MB+512MB) for Cisco MEMU2.5GB 512MB to 2.5GB DRAM Upgrade (2GB+512MB) for Cisco MEMMB-DEF 512MB DRAM for Cisco ISR (Default)