HGAC XXXG-00W0 Wing Gundam Zero

The XXXG-00W0 Wing Gundam Zero (ウイングガンダムゼロ Uingu Gandamu Zero) (aka Wing Zero) is a mobile suit that appears in Mobile Suit Gundam Wing. 

The first High Grade of Heero’s beloved Wing Gundam Zero from Gundam W, this kit is designed to enable transformation into Neo-Bird form.

Twin Buster Rifle can combine into full form or be split in two, and shoulder vulcans are expandable.