Without them, glass windshields will be a lot weaker.

They've actually been around for a few decades after car manufacturers started to use adhesives to hold windows in place.

But have you ever wondered what they're actually for?

The dots and black band running around the edge of your windshield is called a frit.

It is black painted enamel that is baked on both sides of the glass around the borders of the windshield and it has several purposes.

The frit that's on the inner side of the windshield serves as a contact point between the glass and the car frame and help provide a stronger bond.

The frit that's on the outside acts as a shield against UV radiation to protect the adhesive bond.

If this adhesive is made out of polyurethane, which most grass bond mega deive are, it can become weaker after continue exposure to direct sunlight.

Hybrid polymer based adhesives handle sunlight much better as they have more UV resistance.

The half tone pattern in which the black dots are scattered, helps distribute the temperature evenly and helps prevent optical distortion or lensing that would potentially shatter the glass.

The frit also provides a more polished appearance by concealing the adhesive bond.

Nowadays, cars often have a third visor frit which is placed behind the rearview mirror to block the sun between the two sun visors.

If you want to know more about how a windshield is bonded and glass bonding adhesives, you can watch our video on the characteristics of bonding glass in the description below.