I'm not sure, but I'm using Tasty Vapor Atomic Cinnacide 12mg. AC tends to eat through plastics and rubber. I'm trying to be really genital putting the cap back on, but the top ring is a sloppy mess. I finally wrestled it on and am reserved to not remove it again until the wicks are toast. I still have the two backups in the accessories kit that came with the W, but can tell that those will soon be put to use if this keeps up. The cap on my W is really tight (which I like) even when juiced up for lube. My camera on my phone won't take close ups, but I'll try to get a pic up asap to see if you might have an idea. However, I'm still looking to get a pack of 10 or 20. I just went over to the Kidney Puncher site, but did not see o-rings in the accessories or RBA pages. So, if I'm just missing something (probable!) could you kick the link for the o-rings? Thanks.