Golf balls, for example, are hard to distinguish fake from real from just looking at the outside, but when you look inside, you can see that the counterfeit one is mostly hollow. The real one has a solid purple core.
The counterfeit ball won't absorb a swift swing or roll down the green the way you'd expect.
"Counterfeiters want to make the product as cheaply as possible while still looking passable to you," said U.S. Customs and Border Control Director of Policy and Programs Therese Randazzo.
Experienced golfer Michael Byrnes said the counterfeiters are good.
"The differences are almost indistinguishable," he said.
Byrnes got lured into buying fake clubs online. But the fake club had smaller Titleist lettering, and the number to indicate the size of the club was thicker than the real one.
The real test? Part of the club head is supposed to be made of tungsten, a metal that a magnet won't stick to. So by performing a simple "magnet test," Byrnes confirmed he got clubs made of steel - a cheaper metal.
"This is actually the fake golf club. You can see the magnet easily sticks to that particular club."
The counterfeiters even make golf apparel. To determine if a shirt is real or fake, check the inner packaging. If it's from China, it is likely fake. Officials say that's where most counterfeit equipment is made.
U.S. Customs and Border Control seizes hundreds of counterfeit items every year, and the numbers are going up.
"It's a problem that's very difficult to stop," Randazzo said.
Buying fake equipment can prove to be unsafe for golfers. One counterfeit Cleveland club's shaft bent after one use, and in another instance, the club's head flew off.
Experts say if a subpar club doesn't take your head off, counterfeit stuff will chip away at your game, and it will whack your bank account: Fake golf items aren't much cheaper than the real thing.
To protect yourself from getting stuck with a counterfeit, experts say always buy from an authorized dealer when shopping online. Watch out for deals that seem too good to be true, and look for a label of authenticity on the product.
And always buy with a credit card. Iif you don't get what you paid for, you can dispute the purchase.