help with LUKS header backup

[yudi v <yudi.tux@gmail.com>]

I am trying to back up the LUKS header and LUKS FAQ recommend using
the cryptsetup luksHeaderBackup command.
Cryptsetup man page has the following format

"luksHeaderBackup <device> --header-backup-file <file>"

the following example is taken from the LUKS FAQ.

cryptsetup luksHeaderBackup --header-backup-file h /dev/mapper/c1

i just want to confirm if I am reading this example right.

cryptsetup luksHeaderBackup --header-backup-file     > I understand
the options but the following operands are a bit confusing.

h > is the backup  file name/location in the example
/dev/mapper/c1  > I am guessing c1 here means the hard disk partition
with luks. Right?

I only have one partition that uses LUKS, sda4. It's a GPT disk and
the partitions are as follows

sda1 = ESP
sda2 = EF02
sda3 = /boot
sda4 = luks = rest of the disk.

On my system, there is just /dev/mapper/sda4, I am guessing this is
the devise I need to back up or is it the whole hard drive just like
backing up a MBR.

I am guessing the command I need to use on my system is:

cryptsetup luksHeaderBackup  /dev/mapper/sda4 --header-backup-file
/media/USB_stick


Is this interpretation right?

--
Kind regards,
Yudi