I would like to suggest that anyone who picks up hand blown tips to also go to Home Depot in the plumbing section and pick up an assortment of the smaller sized o-rings. Since these are handblown there are variances in the fit of the bottom lips (base) and sometimes a smaller o-ring or larger o-ring is needed, depending on atomizer and tip.
I had to shave (nail file) a small bit off one o-ring-it was the smallest o-ring I have found. On another tip I left the smallest o-ring at the top (portion that sits against the atomizer) of the base and put one a bit larger at the bottom of the base (the part that goes into the atomizer).
Keep an eye on Berts site bmwjen, when you see prices listed is when they are available. You can also e-mail him at the e-mail address listed on his site and ask for a specific style/shape and color. Reference the first post in this
thread.
