Factory test&matched pair The price is for 2PCS/lot. PSVANE CV181-TII Classic Edition. CV181-TII is double triode, used in voltage amplification circuit, Can be replaced directly by 6N8P and 6SN7GT. Psvane MARK TII Series have two sub version: TII Classic version Or TII Collector version. The difference between Classic version and Collector version : It’s from the same production line, the best appearance, the best electronic parameters and the timeproof tubes will be selected to Collector Version. The standard quality tube will class to Classic Version. There are the same selection method in the vintage tube, like telefunken select the best ECC83 to create E803CC, Mazda select the best 12AX7 to create their 5 star 3 mica 12AX7 for military or other important instrument use case.