This is the first product to utilize Peterson's innovative virtual strobe technology. The concept of this tuner is based on Peterson's proud and exceptional digital rotating strobe disc tuning technology, It combines the latest advancements in modern analog, digital, and display technologies. The VS-1 tuner operates on either three AA batteries or a regulated DC voltage from an AC adapter. Depending on your region, the appropriate AC adapter may be included when you purchase the tuner. In either case, the AC adapter must supply a regulated DC voltage of 3.0V to 4.0V from the AC power supply voltage being used and be able to handle a current of at least 180mA (500mW). The DC IN jack requires a standard 2.1mm/5.5mm plug with a positive terminal. Adapter missingCondition: No problems with use. Parts to be noted: Adapter missing. Accessories: None. Warranty: No warranty. Sold as is.