This Victron Energy Orion High Power DC-DC converter is a high output voltage converter for reducing the voltage from a 24V battery source to a nominal 12V output. This is useful if you have a 24V battery system and want to run higher load 12V appliances from it (which are more readily available than 24V appliances).
There is a wide input voltage range of 18-35V 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 70A but up to 5 units can be parallel connected to increase output. There is also a remote on/off facility, so you can activate or deactivate the converter manually using a low current switch, or automatically using a battery +ve signal (e.g. switched ignition feed). There is a very low off-load (standby) current of <20mA and the unit has M6 bolts for easy connection of larger cable.
Commonly used in trucks and other agricultural & commercial vehicles, larger motorhomes, horseboxes and larger boats that have 24V starter and/or leisure battery systems.
Features

High output
Remote on/off
Wide input voltage range
Adjustable output voltage
Under voltage shut-down (battery protection)
Can be parallel connected for higher output