Find Boolean operators help

I was reading this find guide and I saw something with the -and option that I don't think is correct. Do you need the -and option in this?

$ find /mp3-collection -name 'Metallica*' -and -size +10000k 

I found my file that was bigger than 500 MB with and without the -and option.

~ $ find / -iname 'ifn*' -size +500M 2>/dev/null
~ $ find / -iname 'ifn*' -and -size +500M 2>/dev/null

Tips For Linux - How to find files in Linux using 'find'

the "-and" is implied/default if you dont specify the "-or", so you dont really need to specify it in your find statement