perhaps a stupid question, but
WHY ON EARTH WOULD YOU NEED THIS CONTRAPTION?
arena playing? outdoor playing?
I just can't imagine using something like that. then again, I haven't been in every playing situation imaginable. still, it seems odd to me. the bass drum is the only drum part I have no problem feeling or hearing.
In larger venues and outdoor events, and/or in loud bands, the bass drum is usually the first thing the drummer has problems hearing. In the past, drummers have solved this by using drum monitors, with speakers blaring right next to their heads, often boosted to very high levels since the low-end sound of the bass drum doesn't cut through the mix as well. This can lead to hearing damage.
These shakers are a brilliant innovation. They provide the physical sensation of a high-volume low-pitched sound, without creating any actual sound - hence your hearing is protected, but you can still feel the balls and punch of your bass drum. Bass players love these too, mounting them on sheets of plywood and standing on them when they play.
It may seem odd, but if you've done much high-volume playing, these devices are a godsend!
