Resistance bands are a popular workout tool that can help tone every muscle in your body. Millions of people use them safely, but can they be dangerous?

Former Nevada Sen. Harry Reid, 79, claims his life was ruined after he used an exercise band and he's suing the manufacturer of the particular one he used — TheraBand.

The incident took place on New Year's Day in 2015, Reid said, who claimed the device slipped from his hand while he was using it, causing him to fall and smash his face against a bathroom cabinet.

“I hurt myself really bad,” he testified last month at trial, according to The Associated Press. “I spun around. I can’t tell you more specifically. I hit the counter.”

He broke his eye socket and lost the vision in his right eye, according to the lawsuit. He took a hiatus from the Senate and for months afterward wore an eye patch and later dark glasses. He underwent surgery, but he said his vision never fully recovered and he can only tell light from dark in one eye.

Reid claims the incident even affected his decision to retire from the Senate.

But the company is pointing the finger at Reid — attorney Laurin Quiat, who's representing TheraBand, said he was not using the device properly and the company shouldn't be blamed for his injuries.

“All I know, if it had handles, it wouldn’t have slipped out of my hands,” Reid testified.

“Because you wouldn’t have accidentally let go of the band with the handle as opposed to a band without handles?” Quiat asked.

“If there were handles, it wouldn’t have slipped out of my hands,” Reid replied.

The trial is ongoing.

Personal trainer Kent Edwards at Crunch Fitness showed Inside Edition producer Alison Hall how to use the band.

"You don't want to anchor it to any unsecure surface, such as a door handle," Edwards said. "It could easily just pop right off."

Some bands have handles, he added, but if they don't, make sure to wrap it around your hand.

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