Pictured from left to right: red Magnetic roller, red Hard Mesh roller, pink Perm Rod. I used pics to secure the mesh roller in place as well as to prevent the perm rod from flipping over. All three rollers/rods are the same size barrel diameter.
Looking closer at the perm rod, doesn't it look solid and heavy?
But without a doubt, the cheaper and the thinner the plastic of the roller, the less firm the set will be. So I do trust the Diane brand for rods and rollers.