People compare them to Shellac a lot but I've never really listened to Shellac. I can't think of any way to describe them other than ROCK (maybe noise rock?). There's glimmers of bluesy guitar and punk, but not much. They're laid back, songs tend to stick to a single groove, but at the same time the rhythm section is heavy as fuck. In And Out has a really cool dark atmosphere that Old Wounds didn't have that is making me fall in love with it. The last song makes cowbell sound menacing!
Post-hardcore is the vaguest of labels but if it includes these guys, These Arms are Snakes, Gospel, La Dispute, and Trophy Scars then it's def my favourite genre right now, although the similarities that tie those bands together are a little iffy.