Can a steel section slide come in direct contact with a slide plate or do you always use two slide plates; where one is attached to support and the other is attached to the supported element?

The reason for the use of slide plates is to reduce thecoefficient of friction between two surfaces. So to use an unpolished steelsurface, defeats the purpose of reducing the coefficient of friction.

Glass Filled Slide Plate
Glass Filled Slide Plate
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