Voltage indication
Transmitters that allow you to
display the voltage of the on-board network, so as not to accidentally completely discharge the battery. Or to indicate the corresponding parameter for older cars that do not have such a function.
Max. memory card / flash drive capacity
The maximum size of a memory card or USB-drive (flash drive) supported by the transmitter.
For more information about memory cards and flash drives, see "Cart Reader" and "USB Input", respectively. Here we note that a modern FM transmitter can support two types of media at once; in such cases, the volume limit is often relevant for both flash drives and memory cards, but this nuance does not hurt to further clarify the documentation. Anyway, this limitation is primarily due to the fact that a higher storage capacity requires a more powerful hardware; in addition, there are nuances associated with individual subspecies of memory cards. Anyway, it is impossible to exceed the maximum allowable volume — this can lead to malfunctions and even to hardware breakdowns.
Media support
File formats supported by the FM transmitter.
Almost all models support the MP3 format, which is the most common modern digital audio format. Some devices are also capable of working with WMA — this is also one of the main formats, but for a number of reasons it is used much less often. And even less common is compatibility with WAV — this format provides higher sound quality, but with FM broadcasting this advantage is lost, and the files themselves take up noticeably more space than MP3 and WMA.
