100% compatible with my Cisco routers. Haven't had any issues what so ever. I have already purchased more for my other routers. Would definitely buy again.
This memory is non-ECC Memory which is not compatible with Cisco 2821 Router which uses DDR ECC SDRAM Memory.
The label on this memory was tampered with a new label to show MEM2821 and MEM2851 but the original sticker underneath was not removed. Good thing my Router still works when I uninstall this Memory.