Inspection stamps of the same value issued by another state shall be accepted in this state in lieu of the stamps required by this chapter, when attached to an article of bedding, before shipment from the other state, upon satisfactory proof to the director that the requirements in the other state as to quality and inspection of manufactured articles and materials are substantially equal to the requirements of this state; provided, that the stamps of this state are likewise accepted in the other state when attached to articles or materials manufactured in this state.
R.I. Gen. Laws § 23-26-23