GLC-BX-D= SFP Transceiver DOM - 1000Base-BX-D Singlemode

Cisco 1000BASE-BX10-D. Maximum transfer distance: 10000 m, Wavelength: 1310 nm. Safety: Laser Class I 21CFR1040 LN#50 7/2001; Laser Class I IEC 60825-1, Certification: • IEEE 802.3z • IEEE 802.3ah . Weight: 75 g. Transmit power range: -3 - 9 dBmW, Dimensions (WxDxH): 13.4 x 56.5 x 8.5 mm, Connector(s): Single LC/PC/UPC

https://www.cisco.com/en/US/prod/collateral/modules/ps5455/ps6577/product_data_sheet0900aecd8033f885.html

The industry-standard Cisco® Small Form-Factor Pluggable (SFP) Gigabit Interface Converter is a hot-swappable input/output device that plugs into a Gigabit Ethernet port or slot, linking the port with the network. SFPs can be used and interchanged on a wide variety of Cisco products and can be intermixed in combinations of 1000BASE-SX, 1000BASE-LX/LH, 1000BASE-ZX, or 1000BASE-BX10-D/U on a port-by-port basis.

The 1000BASE-BX-D, compatible with the IEEE 802.3ah 1000BASE-BX10-D standard, operate on a single strand of standard SMF.
A 1000BASE-BX10-D device is always connected to a 1000BASE-BX10-U device with a single strand of standard SMF with an operating transmission range up to 10 km.
The communication over a single strand of fiber is achieved by separating the transmission wavelength of the two devices: 1000BASE-BX10-D transmits a 1490-nm channel and receives a 1310-nm signal, whereas 1000BASE-BX10-U transmits at a 1310-nm wavelength and receives a 1490-nm signal.

The GLC-BX-D SFP also support digital optical monitoring (DOM) functions according to the industry-standard SFF-8724 multisource agreement (MSA). This feature gives the end user the ability to monitor real-time parameters of the SFP, such as optical output power, optical input power, temperature, laser bias current, and transceiver supply voltage.