Can`t be bought separately
Can be sealed by sealant
12\15, we do not recommend
We got two DRIFT MANIAC red nipples for two years.
They do get sealed pretty quickly (Continental sealant).
Once fixing bolt got loose, so we could not inflate tire during race. It does not look like a product issue, but we would mention it anyway.
Right now you can get them only with tubeless tape. We do believe that tape is not even close to good one (our etalon is Stan`s yellow tape).
We could recommend this nipples only in they would could be bought separately for approx. 5$