One SEEC HQSN-4U active power filter in a very good condition. The HQSN-4U is a high grade AC-MAINS High-End Inline filter with high precision, and great improvement of the AC supply voltage characteristics to apply to your audio equipment. The rated load at 230VAC is 850 Watt, and at 125VAC 550 Watt. Speaking in terms of music: A level of dynamics, true detail and clarity are immediately appreciated for the trained listeners. Superb high detail and articulation at low levels. This filter can also be used to connect into the AC line of electrostatic loudspeakers, on TV sets, or LCD-projectors for less noise in the picture-screen, or with Computers to “protect” against voltage spikes to avoid damage as much as possible. Uncompromised technology was used. Making use of this new AC-Inline filter system designed by SEEC for professional applications is strongly advised by audiophiles, because the original line frequency and voltage..50/60Hz..will be conditioned and will not enter the equipment in raw condition causing also interference inside enclosures. This is audible by a more precise/cleaner stereo impression. Instruments obtain more horizontal and vertical staging and a real added substructure. There will be more need in the future to filter the AC supply voltage (90V-240VAC), because distortion will only increase. Serial number is NL98084U. Retail price is 350 euro. The original box is included.