What's my Dell Service Tag

Recently come across this command which allow me to get the service tag for my Dell machine without crawling under my desk.

The command is

wmic bios get serialnumber

http://www.dell.com/support/article/uk/en/ukbsdt1/sln268357/how-to-locate-system-service-tag-using-command-prompt?lang=en

I have tried it on other brands too.  As it seems, it works for Acer machines too.