Buttkicker BK-mini-CT Mini Concert Tactile Transducer Shaker Excellent for project and home studios and in-studio playing Great for keyboard players, or any musician using an in ear monitoring system Designed by musicians and studio engineers Patented magnetic suspension makes it more powerful, musically accurate and long lasting than any other shaker or tactile transducer that uses voice coil technology 3 in high x 4.75 in wide; 2 pounds