I broke mine on the maiden flight and HK never stocks them.
This is essentially a copy with a few improvements.
-slots in cone for venting, not the ugly tip cut off like the original
-better shaped, tighter fitting cutout for the propeller
-better webbing on base from center to outer (original had a large slot hole that made it weak). multiple holes instead of slot hole
*Note: I have not tested to ensure enough airflow will get to the motor to prevent it burning up. I intend to do so at my earliest opportunity.
*the most trouble I'm had thus far is getting the 2 screws in without ripping off the bosses. I am thinking about making the screw depth shorter by thickening the material the go through on the cone. Also, there may be other ways to strengthen the 2 bosses I'm not aware of...
*2/17/2015: revved both, I beefed up the screw bosses, thickened the web on the cone, and enlarged the screw holes by 0.009
*2/18/2015: I am planning to do a 4 screw version of this to better seat the cone against the base
*3/16/2015: updated/revved both parts for better fit to one another.