they are like a patcher it download for you all of the info from teh latest data in KOREAN cuz originaly Ragnarok is Korean...its on my forum at something like...

http://vigilancero.s4.bizhat.com/vie...um=vigilancero

make sure you get the latest one which is 1010

its kinda hard explaining what each do...you just know that you need both of them to play...

*edited*

Kro and Sak EACH cost 1G