I received three sets of these, and I am happily surprised by their function.  The toe of the shoe tree is split down the middle and expands side to side as the heel is pressed in.  This helps to keep the toes of you shoes expanded in all directions.

The tension in the spring is strong enough to make the shoe three functional but not so strong as to damage your shoes.

The cedar in these is highly aromatic, so be warned that you may actually trigger your allergies if you have them!

Yes, these are a little more expensive than I had anticipated, but for the function and initial quality, I am highly satisfied!