For your tweeter ....
DE10 Ceramic, Sens: 107 dB. A very cost effective tweeter driver with a very flat response over the most critical 6 to 16 KHz tweeter range. It won't quite reach 20 Khz, but can you hear 20 Khz? Unless you do not have room inside your cabinet, THIS is the driver to use! Go for the DE120 ONLY if your are replacing a K77 inside a stock Belle, La Scala or Klipschorn! It's too big to fit directly in place of a K77 but it's perfect for a Cornwall, CornScala or in any frame that mounts the tweeter to the side of the mid-range horn. Mylar diaphragm.
DE120 Neodymium Ring, Sens: 106 dB. With it's small Neodymium magnet it will fit directly where only the stock K77 would fit. It WILL go well above 20 Khz. Mylar or Titanium diaphragm (DE120TN).
DE110 Neodymium Ring, Sens: 106 dB. With it's small Neodymium magnet it will fit directly where only the stock K77 would fit. Guaranteed go above 18 Khz. HT Polymer diaphragm.
For midrange or 2-way high frequency driver....
DCM50 Neodymium Ring, Sens: 108 dB. This driver was designed for the 400 Hz crossover required by the Klipschorn.
DE85TN Ceramic, Sens: 107 dB. This driver is perfect economy full range driver.
DE750TN Ceramic, Sens: 107.5 dB. The "flagship" full range driver from B&C.