Fiber optic converters.
product details:
item: fiber optic converter
model: leohtb-gsm-dx
specifications: 1000m/sm/dx/20km/external power supply
1000m: likely refers to 1000 mbps (gigabit ethernet) speed.
sm: indicates single-mode fiber optic cable.
dx: likely refers to duplex, meaning it uses two fiber strands for transmitting and receiving signals.
20km: indicates a maximum transmission distance of 20 kilometers.
external power supply: requires an external power source.
quantity: 2 pieces