While I have not tried Ken's product, I have heard good things about it. It appears to be good quality and should produce good results. It has some advantages over some other zappers but also has some disadvantages.
My preference is for a zapper with 2 or more frequencies as user surveys have provided evidence that using 2 frequencies produces better results.
I also see that he uses alligator clips for connections which is convenient but not good in my opinion.
I also think that he is just slightly over priced for what goes into the product.
Some of the others on this forum who have used it may have other opinions.
I will say that is should be far better than the $10 zapper from zapperplans.