"Permission denied" error when using sudo for writing image to /dev/sdb on Debian

I am confused as to why I am getting the following error: $ sudo zcat firmware.A20-OLinuXino-Lime2.img.gz partition.img.gz > /dev/sdb bash: /dev/sdb: Permission denied Shouldn't sudo be able to run any command? Why can't it run this one? I am attempting to install Debian on my A20-OLinuXino-Lime2. Thank you so much for any support you can provide.