Here you will find a list of USB sticks, that has been tested to work with Gotharman instruments.

Gotharman instruments are using a DOS based USB system, made by FTDI called VDRIVE2. Unfortunately this system is not compatible with all USB sticks. If you need to format a USB stick, please do a FULL FAT32 formatting, DO NOT USE QUICK FORMATTING!!!
Kingston DataTraveler 100 (G3)

16GB and 32GB models has been tested to work right out of the box. No formatting needed.