This topic provides a brief overview about USB bulk transfers. Each USB transfer is one packet, which can be up to 64 bytes if using bulk type.If you want to send more than 64 bytes, you have to use multiple packets. Bulk Transfers are used for data which are not of the type Control, Interrupt, or Isochronous. In my project I am configuring USB endpoints (Bulk Mode) for both In and Out from the Host. I have for a long time been wanting to do a Custom USB class driver on the RT106x devices. For bulk transactions, the maximum packet size is 64 bytes for full speed. This is actually per USB spec. In this topic, you'll learn about a USB bulk transfer and how to initiate a transfer request from your UWP app that communicates with a USB device. DFU and Audio are probably your best bet for bulk transfers.