Say goodbye to the old-style light bulb.

On Wednesday, it will become illegal to manufacture or import 60- and 40-watt incandescent bulbs because of federally mandated efficiency standards signed into law in 2007 by then-President George W. Bush.

Seventy-five watt and 100-watt incandescent bulbs were phased out in earlier stages, but the coming ban on 60- and 40-watt bulbs will affect consumers more because of their popularity for residential lighting, experts said.

That means the sort of general-service light bulb we’ve used for more than a century can no longer be made in or imported into the United States.

It may not be noticeable until a few months into the next year when those light bulbs are bought and not replaced, but businesses are expecting to provide a bit of education to consumers unaware of the new change.

What does that mean for you?

On the plus side, it means more choices and smaller electric bills. On the minus side, it means an end to dirt-cheap light bulbs and grab-and-go bulb shopping. Now you need to read labels.

The new lighting standards, part of the Energy Independence and Security Act of 2007, were intended to make light bulbs more efficient and reduce the amount of energy needed to power them. They’ve done that, but they’ve also left some consumers confused in the face of all the choices in the lighting aisle.

“You’re used to buying that 60-watt bulb and knowing what it looks like and everything else,” said Cordell Blackmon, manager of the Batteries + Bulbs store in Ohio. Now, he said, customers who buy bulbs in haste often bring them back when they find the bulbs don’t meet their expectations.

Buying the right bulb requires more attention than it used to, Blackmon said. But with a little education and guidance, he said, his customers end up with what they need.

The Jan. 1 phaseout of old-style 40- and 60-watt bulbs is the third step in the change to more efficient forms of lighting. The first step, in 2012, targeted 100-watt bulbs and was followed in 2013 by the elimination of traditional 75-watt bulbs.

Although the lighting law has commonly been called a ban on incandescent light bulbs, lighting experts say that’s inaccurate. The law doesn’t ban incandescent bulbs but only requires them to be more energy-efficient.

What’s more, the law doesn’t affect all incandescent light bulbs, just general-service bulbs – pear-shaped bulbs with a medium base, the kind that for years were used most commonly in the home. A whole lot of bulbs are exempt, including three-way bulbs, 150-watt bulbs and bulbs with narrower candelabra bases that are often used in chandeliers.

The law may be frustrating some consumers, but many lighting specialists and sustainability advocates cheer the innovations it has spurred.