HARRISBURG, Pa. -- In an effort to battle counterfeit inspection stickers, motorists who bring their cars in for inspection are now getting enhanced stickers that, among other things, reveal their authenticity with a rainbow pattern.

State transportation officials unveiled the new stickers Thursday at the Lancaster factory that helps make them.

The stickers feature an "optically variable device," which shows up as bronze in color but reveals a rainbow pattern in direct light, said Pennsylvania Department of Transportation spokeswoman Joan Nissley.

The sticker includes other fraud-fighting features that are not being publicly revealed for security reasons, transportation officials said.

"Law enforcement will be aware of what to look for," said Betty L. Serian, deputy secretary for the department's safety administration.

Serian said the state has encountered some cases of counterfeit stickers, but that "it's not a widespread problem."

State police cited 760 people in 2001 for using counterfeits or altering inspection stickers, said spokesman Jack Lewis.

The state will pay $1 million for Applied Optical Technologies, based in the United Kingdom, to manufacture as many as 13.5 million inspection stickers, Nissley said. The company will perform the first part of the manufacturing work at a plant in Lancaster, then finish the stickers at a plant in Maryland, Serian said.

The contract represents a savings of about $200,000 over the state's previous contract with American Decal Manufacturing Co. of Chicago.