JVC KV-DR305W Instruction Manual page 16

If You Notice a Problem with the Device
Reset the device. Turn off the power by pressing the reset button
on the back of the device with the tip of a thin paperclip. Press
the power button once again to turn the device on again.
SD Cards
Cards supported by this device
Standard
Capacity
Speed class
File system
Precautions for Using SD cards
When using a commercially available SD card, also check the
instructions supplied with the SD card.
Be sure to format (initialize) an SD card with the device before
use.
SD cards have a product lifespan, such as the number of times
that writing can be performed. It is recommended to replace
the SD card with a new one regularly depending on the usage
conditions.
When inserting and removing an SD card, confirm the
orientation, do not bend it, and do not apply a strong force or
impact to it.
Do not directly touch the contact part with a hand or metal. The
stored data may be damaged or lost due to static electricity.
Be sure to back up (copy) the required files in the SD card to a
PC or other device. The saved data may be lost due to the usage
conditions of the SD card. Please note that JVCKENWOOD
cannot compensate for any damages arising from the loss of
saved files.
Format the memory card periodically.
Do not remove the memory card while recording or during
playback because it may corrupt the data on the memory card.
The device may not operate normally if you use an SD card that
was used by another device, such as a computer or digital
camera. Format the memory card in the device.
Depending on the specifications of the memory card, the
reading and writing speeds for the device's data may differ.
microSDHC
4 GB to 32 GB
Class 10 or above
FAT32