A standard bracket is approximately 4.75" from top to the bottom while a low profile bracket is measured at 3.2"
The height for low profile bracket is approximately 3.2”. The height, size and retention bracket details for Low Profile PCI as
developed by Intel and adopted by PCI-SIG are almost identical with
those defined by Intel for the Low Profile version of the Communication
and Networking Riser (CNR) Specification. For detailed information, please refer to the URLs below for more information.