The smaller sizes have the soft metal "T" arm that bends and is easily cut to fit art objects. - The top bars are made of 1/16” softened metal and can be bent fairly easily. The upright is made of 1/8” metal and would usually need pliers to bend. They are mounted in .5”H acrylic, either clear or semi flat black. They are not glued into the base (some are in tighter then others), so height adjustments can be made by carefully removing them and cutting them down. Also it may be easier in some instances to work with the armature when it is not in the base.
The 12"H T-arms are more rigid and are not softenend. These are harder to bend but will support more weight. The upright is about 1/4" and the top bar is about 1/8".