This is the "550b" EQ for the API 500 series. * Current model (2019) * Enables natural and effective equalization. * Recommended for those who own a 500 series rack. Product Details 【Main Specifications】 * Brand: API * Model: 550b Equalizer (500 series module) * Type: 500 series module (*A separate 500 series rack is required for use) Condition Operation confirmed, working well. Please forgive minor scratches and small marks from normal use, and rack mounting marks. No noticeable damage. Please consider this item with the understanding that it is used equipment. Although operation has been confirmed, please refrain from purchasing if you are overly sensitive, to avoid any problems. Accessories * Main unit * Original box, 50th Anniversary Please comment if you have any questions.