Wish I could give you a definite answer on that tepicky. The machinist makes the J-tanks in house on a daily basis, and we add them to stock as soon as he brings them up (usually 5 or so at a time). I never really know the color/size of the tanks he's making until I see them. When something is out of stock on the site, you always opt for e-mail notification when it comes back in stock... Unfortunately in the case of the J-tanks, there is no option for notification based on a specific color. So if you want a 5.5ml black tank, you're probably best off selecting the in-stock notification for 5.5 ml tanks (takes about 10 seconds) & then jumping on the site when you get the e-mail so you can see what colors have been added.