Sonitus Acoustics The Kicker 2.0 22"x18" Pillow

the sound is great, simple and efficient. It had a great impact on the sound of my kick.
My only gripe is if you transport your bass drum vertically in a bag or a case, the pillow tends to fall inside the drum. A simple velcro attachement option that would be included in the package would probably solve this pesky issue. That's what I did personally, I put 2 stripes of velcro inside the shell and on the pillow and the Kicker doesn't move anymore. But even if it is sandwiched between the 2 skin, it's not enough to keep it in place during transport.
Other than that, 100% recommended, as you can put a flat boundary mic on it. I would recommend the Thomann one. Very good mic for the price. You should see my review on it :)