Usual you need to use 2 pieces UT-277 at the same time.
Model: (Pls leave the message which interface you need)
277SM: single mode (Transmission distance 20KM)
277MM: multimode (Transmission distance 4KM)
Interface optional: SC; ST; FC
Power plug standard: US standard; EU standard (If you need UK standard plug, please contact us or leave a message. )
Package included: 2pcs x UT-277