Pack of four - Genuine Cisco X2-10GB-SR 10GBASE-SR 10 Gigabit Ethernet Transceiver Module.
Specifications:

10Gbps data rate over multimode fibre (MMF)
850nm wavelength
SC duplex connector
Up to 300m on OM3 fibre, 400m on OM4
Hot-swappable
IEEE 802.3ae compliant
Digital diagnostics monitoring (DDM)

Compatible with Cisco Catalyst 3560-E, 3750-E, 4500, 6500 series switches, Nexus 7000 series, and other X2-equipped platforms. Interoperable with 10GBASE SFP+, XFP, and XENPAK modules on the same link.
Pulled from working Red Bee Media broadcast infrastructure. Untested, sold as used.