The USB-GDROM is an ODE by the Russian team 3DO Renovation. This team is also responsible for 3DO ODEs (FZ1, FZ10, and Goldstar).
This ODE is a plug-and-play, all-in-one solution that allows you to load content from a USB storage device. The price ranges from $150-180 USD depending on the current BTC exchange rate. By contacting the 3DO Renovation team directly, you may have the option to purchase via PayPal.
Due to the similarity between the two products, the 3DO Renovation team has provided a comparison chart between their USB-GDROM and the popular Dreamcast:GDEMU. Please note that this comparison chart is considered to be partially outdated, namely the maximum capacity for the selected storage medium (GDEMU users report using SD cards up to 1TB in size).
USB-GDROM can be installed in both VA0 and VA1 model Dreamcasts. Although not required, it is recommended to remove the 12V regulator to reduce heat as the GD-ROM emulator doesn't make use of it.