DESC: Heavy Duty TENS Century 2400A single mode preset TENS unit. The pulse width, pulse amplitude and pulse frequency are adjustable. This is a dual channel unit, which allows you to use four electrodes at a time (two electrodes per channel). The TENS is portable and may be clipped to a belt, shirt pocket, bra or other clothing. Features:• Electrodes: 2" x 2", 4/pkg• Channels: Dual, isolated between channels• Dimensions: 1" x 2.5" x 3.75"• Weight: 4.6 oz (includes battery)• Power Source: 9V battery• Battery Life: 70 hours average usage (alkaline)• Wave Form: Modified square wave with zero net direct current (DC) component• Pulse Amplitude: 0 - 80 mA each channel, adjustable (500 ohm load)• Pulse Frequency: 2 - 150 Hz, adjustable• Pulse Width: 60 - 250 microseconds, adjustable• Maximum Charge: 20 micro coulombs per pulse Includes:• One pack of 4 electrodes • 9V Battery • Instruction manual • Lead wires • Hard shell case Warranty:• 1 year on unit