I have 5 of the spirals I bought from the local garden center a few years ago. They are 5' tall and are a very strong metal of some sort. They do indeed work but the drawback is that you must prune the tomato plant down to a single stem. This is great if you would like to produce a very small number of very large tomatoes per plant but otherwise it is not too practical. They are also too short for the tomato plants we grow in Tennessee so if I use them, I have to top the plant out at 5'. They work pretty good for cucumber vines but are a little short for that purpose as well. I am sure I will find a good use for them, eventually.
I support most of my plants with a simple trellis system. I go to the local lumber yard and buy some 10 foot long 2x2's. I use a power saw to put a point on each one. I get out the ladder and a sledgehammer and drive them down about a foot into the garden soil and space them about 10 feet apart. I then attach nylon string trellis (from the local co-op) with thumbtacks or staples. My garden is wide enough for three of these stakes across and they will easily support 6 large plants, fully loaded. I prune the plants to about 3 main stems and get both large tomatoes and good production. I would not recommend doing this yourself if you don't have someone to hold the ladder steady, if you are small of stature or you are physically challenged by age or infirmity since climbing a ladder and then driving stakes down with a sledgehammer takes considerable balance and strength.
Lee Hall Zone 6B - Tennessee