If oyu already have a G36 then youre gonna need
http://redwolfairsoft.com/redwolf/ai...l?prodID=17072
and i imagine a shorter outer / inner barrel. aaand one of these
http://redwolfairsoft.com/redwolf/ai...l?prodID=22697
besides the holes it does look like a K due to the barrel length. Could be wrong and probably am