This Victron Energy Orion-Tr Isolated DC-DC converter is a compact voltage converter for reducing the voltage from a 48V battery source to a nominal 12V output. This is useful if you have a 48V battery system and want to run 12V appliances from it (which are more readily available than 48V appliances).
There is a wide input voltage range of 32-70V ensuring that the output voltage remains stable even during charging and discharging, and the output voltage is adjustable between 10-15V via a potentiometer. This model has a nominal current output of 20A (240W), but an unlimited number of these units can be parallel connected to increase output. It features full galvanic isolation of the inputs and outputs and has a remote on/off facility, so you can activate or deactivate it manually using a low current switch, or automatically using a battery +ve signal (e.g. switched ignition feed). There is a low off-load (standby) current of <80mA and the unit has screw clamp terminals, so is simple to install with no special tools required. 
Commonly used in off-grid and home Energy Storage Systems (ESS) that use 48V battery banks or 48V modules.
Features

Galvanic isolation
Remote on/off
Wide input voltage range
Adjustable output voltage
Short circuit proof output
Overload protected output
Can be parallel connected for higher output
High temperature protected
Low voltage shut-down (battery protect)
IP43 protected
No special tools required for installation