Power Barrels Secret ?

Ok, I know this is a site of composers not instrument builders but I want to know if any of you have one of those "Power Barrels" on his clarinet,

Those Barrels make your clarinet to sound louder, I tried to get one but I just can't find it, only common barrels so if someone can tell me more or less how are the inner walls of the barrel I will make one.

I already modified a mouthpiece with candle wax, I made a higher baffle and it works, sounds louder BUT, as expected, it gives me a lot of edge, almost like a bright sax tone, I suppose those barrel give the louder sounds without loosing the true clarinet sound...

An small description, a photo of the internal design is all I need....

as you can see, the inner walls are not visible...