The FlushDaddy Long Life Side Entry Fill Valve with 1/2" Brass Thread is a plumbing component used in toilet cisterns. 

Here's a breakdown of what it is:

1. Side Entry: This refers to how the valve is installed in the toilet cistern. Instead of entering from the bottom, the side entry valve is installed from the side of the cistern, which is ideal for certain cistern designs where bottom entry might not be possible.

2. Fill Valve: A fill valve is a crucial part of the toilet cistern mechanism. It controls the flow of water into the cistern after a flush and refills it to the desired water level. It automatically shuts off once the cistern reaches the proper level.

3. 1/2" Brass Thread: This indicates the size and material of the valve's thread. A 1/2-inch brass thread is a standard size for plumbing connections, providing a secure, leak-resistant attachment point for the valve to the water supply line.

In summary, the FlushDaddy Long Life Side Entry Fill Valve with 1/2" Brass Thread is a durable, side-entry fill valve designed for use in toilet cisterns, with a 1/2-inch brass threaded connection for secure water supply installation. It's designed to be reliable, ensuring efficient cistern function.