CHICAGO, IL (CBS) – New sunscreen labels are apparently confusing a lot of customers.

Researchers from Northwestern University Feinberg School of Medicine surveyed more than 100 people and found only 43 percent understood the definition of “sun protection factor,” or SPF.

Many also didn’t realize that to protect against skin cancer, they need broad spectrum sunscreen, which protects against both UVA and UVB rays.

Furthermore, about half of those surveyed said they bought sunscreen with the highest SPF available, but scientists say that doesn’t mean they’re completely protected.

“Just because you buy SPF 100 doesn’t mean you are 100 percent protected,” said Dr. Roopal Kundu, lead author of the study. “Staying out of the sun is the only way to guarantee 100 percent protection.”

The research is published in the June 17 issue of the journal JAMA Dermatology.