From Only War:
Calixian Infantryman's Portable Communications Transcription Device
While the construction of the Calixian Infantryman's Portable Communications Transcription Device varies greatly from planet to planet, its function is vital. Every Guardsman tithed from a world within the Calixis Sector is expected to have a rudimentary understanding of its operating procedures so that he may communicate when Vox-operators are not available. Typically a gripped cylinder with a reservoir or staining liquid, the device has also been manufactured successfully on primitive worlds such as Iocanthos using soft breaking metal or fissionable residue encased in a strain resistant substance, usually milled on site. When a staining liquid is used, it can be manufactured from a variety of substances found throughout the Calixis Sector including, but not limited to, flora/fauna compression, animal excretion harvesting, or synthetic means. This source can often affect the hue of the staining liquid.
The "por-com," as many Scintillan regiments have come to call it, is typically issued with locally rendered Calixian Infantryman's Portable Communications Notation Devices. These can be harvested from fauna rendering processes or created synthetically.
A Poor Craftsmanship Calixian Infantryman's Portable Communications Transcription Device is unreliable. Whenever a Guardsman wishes to make use of one, he must roll 1d10 on a 1 or 2, the device fails to function. An Ordinary (+10) Tech-Use Test will allow the Guardsman to perform the Drusian Litany of Gesticulation, calling on the power Saint Drusus to restore the device to working order.
A Best Craftsmanship Calixian Infantryman's Portable Communications Transcription Device functions even in locations without gravity and has multiple reservoirs that
hold different pigments of staining liquid.