Brian Harman had played things close to the vest all week at Royal Liverpool when asked exactly what he’d figured out with his putting over recent weeks.

“I can’t tell ya,” Harman told NBC Sports’ Cara Banks on Saturday evening while holding a five-shot lead after 54 holes of the 151^st Open Championship.

Well, after lifting the claret jug a day later, Harman finally revealed his secret: a new training aid.

“I found this – it's a silly looking mirror, where it's got like a little better release pattern,” Harman said. “I was just kind of cutting my putts too much. I spent a lot of time just feeling the ball, almost hitting like a baby draw with my putter, and it's been really, really good the last month or so.”

Harman said he acquired the mirror on the practice green before the start of a tournament a few years ago, though he couldn’t remember the exact event or year. He didn’t use it at first, but after a poor stretch of putting this spring that included bad performances at Wells Fargo (-0.670 strokes lost on the greens per round) and PGA Championship (-0.302), he was rummaging around in his barn, looking for a new flatstick, when he found the aid.

“There was a time middle of this year to where we were seriously thinking about going to the bullpen and pulling out something different,” Harman said last Friday. “It's been a good putter, but she's been misbehaving a lot this year.”

Instead of switching putters, Harman started working with the mirror. He's been using it weekly ever since, and entering The Open, he had improved from T-67 on Tour in strokes gained putting prior to the U.S. Open to No. 38.

His putting heated up even more at Hoylake, where Harman not only led the field in strokes gained putting (+11.57 for the week), but he also went 58 for 59 putting from 10 feet and in.

Thanks to that silly looking mirror.