Brand NEW! Including 90 Days USA Factory Warranty. The Dayton Audio DS175-PR 6-1/2" passive radiator is excellent general-purpose radiator which allows lower tuning frequencies in smaller enclosures, suitable for replacement or for new construction. Highlights Long-throw suspension system for clean excursion Rugged stamped frame design with rear spider for stability Durable coated paper cone and rubber surround M5 threaded hole simplifies adding mass for lower tuning frequency The Dayton Audio DS175-PR 6-1/2" passive radiator is an excellent general-purpose radiator suitable for replacement or for new construction. A built-in mass disc offers a good starting point for most designs, and a convenient M5 threaded hole (screw included) allows different types of weights to be added if desired. Cosmetically and mechanically, the passives match the Designer Series line of drivers, with a poly coated paper cone and medium-roll rubber surround for clean excursion and long life. The possibilities with these passives are endless, from floor standing two-ways to small active/passive subwoofer systems. Recommended for use in passive radiator enclosure alignments with active drivers from 3" to 6.5" in diameter. Dual passive radiators are recommended for use with 6.5" active drivers. Specifications: ? Fs: 24.5 Hz ? Vas: 0.95 cu. ft. ? Qms: 5.57 ? Cms: 1.15 mm/N ? Rms: 1.0 kg/s ? Mms: 36.6 g ? Sd: 128.7 sq. cm. ? Xmax: 8 mm ? Dimensions: Overall diameter: 6.94", Cutout diameter: 5.63", Depth: 1.88" Note: Adding mass to the passive radiator will decrease Fs and increase Qms. Tip: As a general rule the passive radiator(s) should be able to move double the volume of air as the active woofer(s)/subwoofer(s) in the system. For example: A passive radiator system for a 6-1/2" woofer/subwoofer that has 8mm of Xmax would require 2 6-1/2" passive radiators with 8mm of Xmax. For single passive radiator systems, it is common to use a passive that is larger than the active woofer(s)/subwoofer(s). Product Specifications Nominal Diameter - 6-1/2" Thiele-Small Parameters Resonant Frequency (Fs) - 24.5 Hz Mechanical Q (Qms) - 5.57 Compliance Equivalent Volume (Vas) - 0.95 ft. Mechanical Compliance of Suspension (Cms) - 1.15 mm/N Diaphragm Mass Inc. Airload (Mms) - 36.6g Maximum Linear Excursion (Xmax) - 8 mm Surface Area of Cone (Sd) - 128.7 cm Materials of Construction Cone Material - Paper Surround Material - Rubber Basket / Frame Material - Steel Mounting Information Overall Outside Diameter - 6.94" Baffle Cutout Diameter - 5.63" Depth - 1.88" Bolt Circle Diameter - 6.54" # Mounting Holes - 5 - All international buyers are responsible for all tax, duties and/or customs fees.