's ND25FN-4 compact soft dome tweeter element features high output and smooth, low-distortion sound. The high-strength neodymium motor features an aluminum heat sink for cool operation and reduced power compression. 1" treated silk dome diaphragm Faceplate-free design enables versatile custom mounting High-strength neodymium motor with heatsink and ferrofluid cooling Extremely smooth and extended treble response beyond 22 kHz Perfect for use with a waveguide or custom mounting plate