Scan Speak - R2904/700005 - Ring Tweeter 4 Ohm Revelator

Datasheet

The Revelator Tweeters large roll surround technology represents a breakthrough in 
overall performance, with outstanding off-axis response, high output capability and low 
resonance frequency. Additional enhancements have been made to reduce distortion 
and power compression, such as large neodymium magnet systems for high 
sensitivity, and a careful design to optimise airflow in the chambers.