(WYTV) – Black and yellow can make an eye-catching color combination.

A website that deals with the automotive industry and transportation called Jalopnik said school buses come in no other color and always have black stripes.

The three black rails that run along the sides and back of the bus are called rub rails. Each bus has them and here’s why.

First, they’re an extra layer of protection for the thin walls of a school bus. They’ll absorb the force of a collision and a car from caving in the whole side of a bus.

What’s more, the rub rails are attached at certain spots on the side of the bus: the lowest one is installed at floor level, the middle is opposite the bottom of the seats and the top one matches the top of the seats and the bottom of the window.

Firefighters know this. In a crash, if they can’t reach or open doors or windows, rescue teams know where to cut into the sides of the bus.

If an impact is below the bottom rail, for example, that means it’s below the floor so the students may not have been badly hurt.

The placement, size and color of rub rails can be different from state to state, but the bus’s color is called “National School Bus Glossy Yellow.”

In 1939, a group of engineers decided that particular color was easiest to see during morning and evening bus rounds.