There are at least 2 bands named flag

1)Flag is a Slovakian old school thrash / death metal band formed in 2002

http://bandzone.cz/flag

2) FLAG consists of Keith Morris, Chuck Dukowski, Bill Stevenson, and Dez Cadena and Stephen Egerton.
Formed in 2013, they perform the music of Black Flag. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.