I have been considering some more control in the oxygen department from the 1 1/4 in hole on the side of my UDS. I currently use magnets, but I am not happy with the amount of control it gives me, as the magnets are small rectangular shaped, and do not cover the hole completely, as the side of the barrel is round, leaving little cracks for air to get in. Anyway, do you guys use stainless steel pipe nipples? If not, then what do you use? Also, I have never seen a stainless steel ball valve, what do you use? has it been damaged by the heat? What about the rubber seals in the ball valves, have they been damaged? Any insight would be deeply appreciated.