The Safety Equipment Institute (SEI) is like a special company that helps make sure things we use to keep us safe actually work the way they're supposed to.
Let's say you need to wear a helmet to protect your head while riding a bike. SEI tests the helmet to make sure it's strong enough to protect your head if you fall off your bike.
They test lots of other safety equipment too, like work gloves, safety goggles, and even fire extinguishers. They make sure that the equipment meets certain rules and standards, so we can trust that it will work correctly when we need it to.
SEI is kind of like a safety superhero. They don't design or make the safety equipment themselves, but they make sure the safety equipment we use is reliable and will protect us when we need it.