The HF10RT is the Titanium diaphragm version of the world class HF10AK.  The titanium diaphragm brings a bit of that east coast battle system sound while maintaining the FaitalPro finesse.  If you are building a high output vehicle and want "the sound" of the islands but with better clarity and accuracy of reproduction this is the driver for you. - this is a special purchase, get them while they last at this special price.