How are crease protectors supposed to fit?

Crease protectors are designed to fit inside the toe box of your shoes, with the curved side facing up towards the tips of your shoes. They should fit snugly but not too tight to prevent creases from forming on the toe box.
How are crease protectors supposed to fit?

The Crease Beast Duo

Crease protectors are designed to fit inside the toe box of your shoes, with the curved side facing up towards the tips of your shoes. They should fit snugly but not too tight to prevent creases from forming on the toe box.