Re: 305098 Quad O-ring Home › Forum › Ask A Member › 305098 Quad O-ring › Re: 305098 Quad O-ring frankrUS Member - 1 Year (includes $3 online payment fee)Replies: 6715Topics: 51 July 13, 2018 at 11:44 am #79479 Yes, that’s it. Bill, they are used in the Big Twin carbon seal. marineengine thinks they are worth $16.00 each.