Dayton Audio DAEX30HESF-4 High Efficiency Steered Flux Exciter with Shielding 30 mm Exciter 40W 4 Ohm Dayton Audio's DAEX30HESF-4 steered high flux exciter is one of our most powerful. It has a specially designed neodymium motor system that imparts strong forces on even the most rigid surface for maximum output. For use with medium sized amplifiers, this 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 of only 0.3 mH. Four threaded screw holes are integrated into the exciter's shell and combine with a 3M VHB (Very High Bond) adhesive, 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: 40 watts RMS • VCdia: 30 mm • Nominal impedance: 4 ohms • Re: 3.8 ohms • Le: 0.31 mH • Fs (uncoupled): 267 Hz • Dimensions: 2.25" dia.(2.75" across mounting tabs) x 1.125" H • Adhesive dimensions: 1.25" outside diameter • Weight: 158 grams.