The Notifier FSP-951T-IV or FSP-951T brings several enhancements over its predecessor, the FSP-851T. Firstly, the new model offers improved detection sensitivity, ensuring quicker and more accurate response to potential fire incidents. Additionally, it incorporates advanced technology for better false alarm rejection, reducing nuisance alarms and enhancing overall system reliability. Furthermore, the FSP-951T-IV or FSP-951T features enhanced communication capabilities, allowing for seamless integration with modern fire alarm networks. Overall, upgrading to the FSP-951T-IV or FSP-951T ensures enhanced performance and reliability for your fire detection system.