Ericson said..
Posting from my phone. Sorry if it is not formatted well. Hopefully the picture shows. See the little Nick on the O ring? It's a 2015 Ozone Reo. Is this bit easy to remove and replace?

I buy O-Rings of various sizes from my local bearing place, if you pull that one out with a crouchet hook or similar blunt hook and take it with you they should be able to match it. O-Rings are usually measured in OD (outer diameter) and thickness. If your local kite shop can't supply them they may be able to give you the specs, that looks like a 30x2,5mm judging by the pics but best to get specs if you can or take it with you.

That's the solid raised part on the actual valve and will almost certainly mean the Boston valve need to be replaced.
I have these in stock and can either supply you with one or fit it for you.

Ryan
The Sail Doctor Kite Repairs