Dayton Audio DAEX25SHF-4 Steered High Flux 25mm Exciter 20W 4 OhmDayton Audio's DAEX25SHF-4 steered high flux exciter can generate a force 4 times greater than most standard sound exciters. It has a specially designed neodymium motor system that imparts strong forces, on even the most rigid surface, for maximum loudness. For use with small, Class D amplifiers, the steered high flux exciter incorporates a 4 ohm voice coil to extract maximum power. A wide frequency response is permitted due to this exciter's low inductance. Four screw holes are integrated into the exciter's shell and combine with a 3M VHB (Very High Bond), permitting this exciter to be securely coupled to a wide range of materials, even upside-down mounting and attaching to moving objects. Two solder tabs offer quick, permanent wire attachment. Note: An exciter's frequency response and sensitivity are completely dependent on the exciter's designated surface. Thinner, smaller materials will tend to be louder and create a mid/tweeter response. Thicker, larger materials (with multiple exciters) will be slightly quieter but result in a more full-range sound. Specifications: - Power handling: 20 watts RMS - VCdia: 25 mm - Nominal impedance: 4 ohms - Re: 4.3 ohms - Le: 0.41 mH - Fs (uncoupled): 365 Hz - Dimensions: 2.15" (54.5 mm) dia. x 1.40" (35.5 mm) H - Adhesive dimensions: 0.62" (15.7 mm) outside diameter - Weight: 268.2 grams.