Brand NEW! Including 90 Days USA Factory Warranty. Dayton Audio's ND90-4 compact aluminum cone driver demonstrates the latest advances in high-excursion design processes. When teamed up with the matching ND series passive radiators this driver can produce incredible full sound from compact enclosures. Key Features Full-range 80 Hz to 15 kHz performance Rubber-edged aluminum alloy cone Large excursion capability?4 mm Xmax, 20 mm peak Self-shielded Neo-Balanced motor structure 3/4" 4-layer underhung voice coil with polyimide former 20 watts RMS power handling Dayton Audio's compact aluminum cone drivers demonstrate the latest advances in high-excursion design processes. An efficient, low-distortion Neo-Balanced motor is combined with a rigid yet lightweight aluminum diaphragm, yielding impressive high-impact audio reproduction. Perfect for single point-source applications, or combined in multiples and line arrays. Product Specifications Nominal Diameter 3-1/2" Power Handling (RMS) 20 Watts Power Handling (MAX) 40 Watts Impedance 4? Frequency Response 80 to 15,000Hz Sensitivity 85.7dB 2.83V/1m Voice Coil Diameter 0.75" Thiele-Small Parameters Resonant Frequency (Fs) 90.2Hz DC Resistance (Re) 3.6? Voice Coil Inductance (Le) 0.62mH Mechanical Q (Qms) 5.1 Electromagnetic Q (Qes) 0.72 Total Q (Qts) 0.63 Compliance Equivalent Volume (Vas) 0.037ft Mechanical Compliance of Suspension (Cms) 0.73mm/N BL Product (BL) 3.47T·m Diaphragm Mass Inc. Airload (Mms) 4.3g Maximum Linear Excursion (Xmax) 4mm Surface Area of Cone (Sd) 31.2cm Materials of Construction Cone Material Aluminum Surround Material Rubber Voice Coil Wire Material Copper Voice Coil Former Kapton / Polyimide Basket / Frame Material Steel Magnet Material Neodymium Mounting Information Overall Outside Diameter 4.07" Baffle Cutout Diameter 3.01" Depth 2.39" # Mounting Holes 4 Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion) Sealed Volume 0.1ft Sealed F3 90Hz Vented Volume 0.16ft Vented F3 48Hz - All international buyers are responsible for all tax, duties and/or customs fees.