United debuted their new narrowbody premium (first class) seat which week starts flying on a single Airbus A319 next week, continuing rolling out across the Airbus fleet in the fall (although the retrofit won’t be completed until 2017), and work will begin on ‘many’ 737s and 757s throughout 2016. It appears that while over 200 planes in United’s fleet will get the new seats not every narrowbody will have it. I assume that has to do with projected retirements from the fleet.
The seat appears to add half an inch of width compared to the current Airbus first class seat, at least that’s my read although United claims the cushion width represents a greater increase than that.