Additional Details ------------------------------ Bullet point: 1-1/8" aluminum diaphragm offers remarkable clarity without the typical harshness of metal domes Product description: The Dayton Audio RST28A-4 1-1/8" aluminum dome Reference Series tweeter has remarkable clarity, low free air resonance, exceptional efficiency, and smooth frequency response, a combination seldom found in the industry at any price. The included truncated faceplate allows for tighter spacing between the tweeter and woofer/midrange drivers.