Import duty exemption for lead glass used in lamp components, conditional on importer undertaking and pay-on-demand obligation. Lead glass tubings and rods imported for manufacture of components for electrical lamps and fluorescent tubes are exempted from that portion of customs duty in excess of 40% ad valorem, subject to the importer furnishing an undertaking to use the goods for the specified purpose and to pay, on demand, the difference between duty otherwise leviable and duty paid if the undertaking is breached; the exemption is time limited under the notification.