You will find these small Stem bumpers typically on the bottom of round base patio chairs, chaises and bar stools. These stem bumpers keep the round base of the outdoor chair from making direct contact with the ground. Swivel base outdoor chairs use between 6 and 8 stem bumpers per chair. These stem bumpers are small enough not to be curved. They fit the shape of the tubular metal chair base without the need to be curved. Round patio chair glides and stem bumpers are sized to fit common patio furniture chairs.