If you get a delrin cartomator from nhaler and a depth charge,you can use the tube and a cap from the cartomator for the bottom(its hid from view inside the destroyer)and the top cap for the depth charge and it will fit,and you'll have 2 tanks.The cartomator caps are the same OD as the polycarbonate tube.Thats how I use the destroyer.One cap from the depth charge is just slightly bigger than the other,supposedly one is the top and one is the bottom,however,it makes no difference in how they work.