Check the listing for details. System Sensor B-501 Base Same Day Free Shipping. New. Condition: New. Listed at 22.99 USD. New. Same day free shipping. For more bundles details. Request more information. Bundle of 35 pieces cost $140 dollars. Each piece price is $23.00 dollars System Sensor B-501 white bases is a must-have for any business or facility looking to enhance their fire protection equipment. Made in India, these units are guaranteed to be of top quality and will ensure the safety and security of your property and personnel. Designed specifically for use with fire alarms, the System Sensor B-501 white bases are compatible with a range of different brands and types of devices. Whether you're looking to upgrade your existing system or install a brand new one, this bundle is the perfect solution. And with free shipping included, there's no reason not to invest in this essential piece of equipment today.