need help putting together this hybrid drip tip

[nic_fix]

trinity copa. no instructions. got the two black small O-rings on the stem. got the two black larger O-rings inside the barrel. there is a small red o-ring leftover. where does that go? i figure somewhere in the barrel because i can't imagine the glass sits as low as it is. have no idea where it goes if anywhere. had a heck of a time getting them on too. something this price should come assembled. it is a longshot but if anyone has one id appreciate help. otherwise this thing is not much for looks imo but the clouds from a 510 are the best i have experienced. can see straight down it.