Ngineering Little Bigger Sound Modules are a great solution for adding layout-based environmental sounds to your model railroad. Each Little Bigger Sound module has a pre-recorded sound effect and includes an 8-ohm 1-1/8" 28mm speaker and a 1-1/2 watt amplifier. Audio output is louder than on Little Sound Modules - great for use on layouts in noisy environments. Little Bigger Sound Modules work best on a clean (filtered) 12V DC power supply such as Ngineering No. 514-N3512A.