Due to the overwhelming success of the Baby Tremor and we decided to offer it in an Empty model. Now you can load them with the subwoofer of your choice. This high performance compact 15 subwoofer is the ultimate in power performance and portability for any PA setting. The Baby Tremor was designed with medium sized live sound and DJ setting in mind...compact size with deep bass output. Now you have the power to drop any speaker you want and see how low the bass can go!