Can I use the SFP-10G-LR 10g interface with Multi - Mode fiber?
If you had SFP-10G-LR (long reach) than you would have to use single mode fiber.
SFP-10G-SR Multimode fiber
SFP-10G-LR Single Mode fiber
As mentioned above SR does in fact indicate MM fiber. Make sure you utilize lazer-optimized fiber (50 micron OM3/OM4). Using 62.5 micron decreases usable distance and in some cases does not work at all.
3Anetwork.com keeps regular stock of Cisco SFP-10G-LR, the Cisco 10GBASE-LR Module SFP-10G-LR supports a link length of 10 kilometers on standard single-mode fiber (SMF, G.652).