Radio Tubes Two National 6SL7 TV/7 08/24 Calibrated 60/62 and 60/55 are vintage vacuum tubes suitable for use in various electronic devices. These tubes, made in the United States, come in a set of two and are ideal for vintage audio and video equipment. With a Brand of National and a Type of Vacuum Tube, these 6SL7 model tubes offer quality performance and authenticity for collectors and enthusiasts alike. Made in the United States, these tubes are a piece of electronic history ready to be enjoyed in your vintage electronics collection.