he's a skin, available on the byoc skinpack
https://allfearthesentinel.com/zandronum/download.php?file=byoc_skinpackv2.5.pk3
if you're not playing online, you can create a new folder called skins the drop the filename in thereif you are just drag and drop it along with byoc
the link is broken
Skinpack got updated,replace 2.5 with 2.6 in the link it should work, if not just keep adding numbers or do a search on the sentinels playground
404((
