Brand: Pro Master USAModel: SPT-181S Dome Piezo Tweeters with Coil ExciterCAR OR HOME HIGH EFFICIENCY TWEETERSNow Improved 500W pair (250W each tweeter)Impedance: 4~8 ohmsBUILT-IN CROSSOVERDiameter: 1.45" (37mm)Height: 0.8" (20.5mm)Height with self-adhesive disc: 0.83" (21mm)Height with base: 0.925" (23.5mm)True Micro Domes, Super Small Size fits just about anywhere! For All Audio Systems No Magnetic Field High efficiency with Only 2.8v You Can hear 97db, more sound with less energy! 2 Mounting Options Includes:2 Tweeters 2 Clip-on Bases 2 Double-sided self-adhesive discs Mounting Screws