When I have spoken of recommending that people use the smallest SNS tubing, I am speaking of having the second tube open, as a vent. I know the unit supposedly vents somehow, around the cap, but I could never get it to do that. I found that, either I had to open the other tube to let air in, periodically, or the baby would learn to let go, momentarily, when the flow slowed down. The gurgling sound, as air rushed in, can be a problem, especially with a tiny baby, who can be startled by the noise. Another problem with allowing the vaccum to form is that it results in alot more of the baby's saliva getting sucked up into the bottle. The Lact-Aid does not have those problems and is much more convenient. That, as well as many other ways in which the Lact-Aid is more convenient than the SNS, for moms who need to use a supplementer more than a few times, are why virtually all adoptive moms who have had significant experience with both supplementers, prefer the Lact-Aid. Aloha, Darillyn *********************************************** To temporarily stop your subscription: set lactnet nomail To start it again: set lactnet mail (or digest) To unsubscribe: unsubscribe lactnet All commands go to [log in to unmask] The LACTNET mailing list is powered by L-Soft's renowned LISTSERV(R) list management software together with L-Soft's LSMTP(R) mailer for lightning fast mail delivery. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html