Each of the solid spheres are a single component – that is, the height of each solid sphere is fixed and is not adjustable. Please see the accompanying figure, in which the lowest sphere is on a modified support stem. You may notice that it appears white, rather than clear like the other two rods. This rod was made from a nylon screw in which the head was removed. In regards to the other two spheres, it shows how you can substitute the stems for one sphere with the stem for another. The way to get customized stem heights is to take nylon or Lucite  threaded rods (¼ x 20) and cut them to the desired length. The seal you obtain may not be quite as good as that you would get with the standard stems, but the result should be sufficient. Tips on cutting rods: Put a metal nut on the rod before cutting, on the side of the cut that you will keep. You can run the nut up to the desired cut location and slice through the rod with a knife-like object heated with a propane torch, or you can use a standard hacksaw, coping saw, Dremel rotary tool or similar tools. A saw blade with finer teeth usually makes for better looking and easier to use cuts. Once you have cut the rod, screw the nut off of the rod. This will help shape the threads to the proper shape. A metal file, grinding wheel or similar tool can help shape the cut end(s) to where it will more easily screw into the base plate and/or the neck of the sphere. Another helpful tool is the Xcelite Standard Lead Shear (model 170-M) cutter, or the Super Shear Flushcutter (model 170-D). These are excellent for trimming small, deformed pieces of threaded nylon off the newly formed stem. A good alternative to threaded rods is nylon screws or bolts, which are readily available. Cut the head off of the rest of the screw or bolt per the above instructions. One source of nylon screws and bolts is SMALL PARTS, Inc., 13980 N.W. 58th Court, P.O. Box 4650, Miami Lakes, FL 33014-0650, Phone: 1-800-220-4242. DSC recommends that you do not use metal rods or screws in place of the supplied stems. Also, never use pliers or other tools to tighten phantom parts. If you have to resort to pliers to unscrew a stem or other phantom part, place a soft cloth or folded paper towel between the part and the pliers to avoid scratching it or leaving indentations. Applying too much pressure will crack the phantom parts and void your warranty. Never put pliers on the spheres – they are almost guaranteed to break, and this breakage is not covered by the general warranty.