These wicks are perfect for the straight sided tumbler. I know CS's recommendation was a CD 18, but in all of my testing, I never achieved a full melt pool. So I went up a size and I noticed that the HT is a lot stronger with these too for what I'm using. I use 464 and CS FOs and I am so happy with these wicks. No mushrooming, no soot, and no excessive flame. All in all, a great and reliable product!
When I was researching the straight sided tumbler jars, I didn't see a lot of consensus regarding the wick size so I thought I'd throw this out there! As always, test test test - but hopefully this helps someone!