From the Depths Wiki
Laser Transceiver
Health 100
Armour Class 4
Structural No
Weight 20
Relative Buoyancy +17.9
Size 1x1x1
Material Cost 100

The transceiver can link a multipurpose laser to a distant laser coupler. Transceivers built on and directly above a turret and built on the main vehicle directly below the turret can communicate.

Connects the laser-parts, just as the Laser Connector but over a distance. One Laser Transceiver is required on each end of the connection, but only the transceiver that is connected to the multipurpose laser (whether via laser connectors or other transceivers) must actually point at the other one. There is no limit on range, and the connection can even pass through other blocks.

The transceiver can also link laser systems across subobjects, if one transceiver is placed under the turret pointing directly at it, and another transceiver is placed on the turret any number of blocks directly above the turret. Note that the transceiver on the turret does not actually have to point down - it can point in any direction.