Brand NEW! Including 90 Days USA Factory Warranty. The Dayton Audio ND90-PR 3-1/2" passive radiator makes it easy to tune small enclosures lower without increasing overall enclosure size. With a one-piece aluminum cone, rubber surround, high excursion capability, and easily adjustable mass, this passive radiator is perfect for building extremely compact speaker systems capable of incredible low frequency output. Key Features ? Rigid black anodized aluminum alloy cone ? High excursion capability: 18 mm peak to peak ? Same "family look" as ND Series woofers ? Adjustable mass for a vast range of tuning frequencies Tune small enclosures with Dayton Audio's ND90-PR 3-1/2" passive radiator in speaker designs where a conventional port is not a viable option. This compact passive radiator includes all of the features you expect with larger radiators including high excursion capability, aluminum cone, rubber surround, and adjustable mass. Visually identical to Dayton Audio's popular ND series drivers, the ND90-PR can be used with any small speaker. The threaded rod and included wing nut on the back of the cone makes it easy to add mass to tune the radiator as needed for your projects. Whether you are building a multi-driver array, sound bar, or portable Bluetooth speaker, the Dayton Audio ND90-PR introduces a new range of possibilities. The ND90-PR 3-1/2" passive radiator includes: (1) Passive radiator (2) 7.3 gram disk weights (1) Wing nut Specifications: ? Fs: 53.8 Hz ? Vas: 0.05 cu. ft. (1.5 liters) ? Qms: 6.15 ? Cms: 1.09 mm/N ? Mms: 8.1g ? Rms: 0.44 kg/s ? Sd: 31.2 sq. cm. ? Xmech: 9 mm ? Dimensions: Overall diameter: 4.07", Cutout diameter: 3.35", Depth: 2.39". Tip: As a general rule, the passive radiator(s) should have at least double the displacement of air (Vd) as the active woofer(s)/subwoofer(s) in the system. To calculate Vd: Sd x Xmax = Vd - All international buyers are responsible for all tax, duties and/or customs fees.