The 62-year-old said he sees himself as a sort of referee of retail, tasked with making sure sellers and customers are behaving honestly. Beyond gas station pumps and supermarket scales, he’s also sealed scales used to weigh in middleweight boxers at TD Garden and scrutinized too-foamy beers at Fenway Park. Regardless of venue, he described the work as “total consumer and business protection.”

Oliver is one of the city’s six deputy sealers, inspectors charged with ensuring the accuracy of scales, gas pumps, taxi meters — anything businesses in Boston use to measure products sold by weight, volume, or distance. Businesses can’t use measuring devices until they have been inspected and approved by the city and must have their tools rechecked each year.

In 2022, the division saved Boston consumers nearly $6.9 million in potential overcharges caused by faulty measuring devices and mislabeled merchandise, according to its annual report to the state. Meanwhile, it saved merchants more than $1.2 million in what may have been free product, undercharged because of poorly calibrated gas pumps, scales, and odometers.

And, the report noted, all those savings come at a price of under $1 million a year to operate the entire division.

“The Weights and Measures motto is ‘equity in the marketplace,’” Oliver said, driving back from a Whole Foods Market with a trunk full of weights. “It’s no lie.”

Earlier that Wednesday morning, Oliver demonstrated an inspection at the grocery chain’s South End location.

He arrived around 11 a.m., just before the lunch rush would begin, donning a pair of thick-lensed eyeglasses as he stepped out of the car. He carried a black tool kit a little smaller than a shoe box. Inside, more than 30 pounds of palm-sized cylindrical weights.

That day, the inspector had called ahead, so the store knew to expect him, but sealers usually show up unannounced.

“If they knew we were coming, we’d never find anything wrong,” Oliver said. “I tell them all the time, ‘Look, we’re always coming in here, so be prepared.’”

Inside, he grabbed plastic packages of fried chicken and diced melons, inspecting their advertised tares — the weight of the packaging itself, which must be subtracted from the total before any per-weight price is calculated. Part of Oliver’s job involves “re-weighing” these items to make sure what’s on the label measures up to reality. The fruit cup was a perfect match, but the chicken, labeled at .86 pounds, measured in at .85 — a discrepancy Oliver said can be attributed to changing moisture content as temperatures rise and fall, but is still worth noting.

“How you doing?” Oliver asked a worker standing behind the prepared-food counter in the same booming, friendly tone he uses to greet co-workers walking through the office.

Then, a matter-of-fact demand: “We’re going to use your scale.”

He stepped behind the counter and began to disassemble the equipment, pulling off the weighing tray and inspecting its underside. Workers squeezed behind him, pushing carts of steaming food.

Oliver zeroed out the scale. Then, one by one, he placed his weights, performing what he called a “build-up test”: a half-pound, 1.5 pounds, 2.5, all the way to 20.5 pounds. He slid one weight around the scale, making sure there were no discrepancies or dead zones.

“Usually, if it’s out right away, the error gets worse as you put weight on it,” he said, dropping on a final, 10-pound cylinder. The scale, last inspected in February, according to its sticker, was still “dead on,” he declared.

Last year, the division sealed — approved — 3,209 scales, per its report. It condemned an unlucky 13, slapping on bright red stickers and banishing those machines from business, at least until they can be proven accurate.

But despite the once-a-year — or more — inspections, businesses seem to pay little mind to the division, according to Jon Hurst, president of the Retailers Association of Massachusetts. He said he has heard “nothing in recent years” about Weights and Measures.

Hurst questioned whether the division, “created decades and generations ago,” was still relevant in the face of modern technology.

“As long as they’re being fair, so be it,” he said. “It’s kind of one of those no-news-is-good-news things.”

On top of certifying or condemning measuring tools, Weights and Measures is responsible for ensuring products ring up at the advertised cost, so there are no surprises at checkout. For that test, inspectors use a hand-held bar code scanner to check a random selection of items.

Oliver started with a can of Guayakí Yerba Mate, listed at $3.19.

“Pray that this scans correctly,” he said, squeezing the scanner’s trigger. A tense few seconds followed. $3.19 flashed on the scanner’s screen. “And then we just continue on and do 100.”

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Around the corner, Oliver held a 24-ounce tub of “birria-inspired” beef soup. The scanner beeped, Oliver waited, then he squinted at the screen.

“Yep, this one’s wrong,” he said.

As it would turn out, the item had simply been misplaced, and there was no price tag on the shelf for that particular soup. That is inconvenient, Oliver explained, but since there was no price advertised, he would be unable to prove a difference.

At least 98 out of 100 items scanned need to be priced accurately for a business to pass this part of inspection. Last year, the division inspected sticker prices at 429 stores; 318 passed, according to the annual report.

The city fines merchants $100 for every mislabeled product, with no limit to the total fine. Oliver said he’s issued fines of up to a few thousand dollars, but the goal is to “fine people into compliance,” not to generate revenue.

“We just want correction. We just want it to be right, that’s all,” he said. “We don’t need your money, the city’s got plenty.”

Weights and Measures, quartered in back of the Inspectional Services Department’s office on Massachusetts Avenue, is one of the city’s oldest divisions, said Elaine Vieira, head of the division. She came to the office nearly 20 years ago, starting as a clerk before working up to Boston’s sealer of weights and measures. Before joining, she said, Vieira had not even heard of the division.

She remembers thinking, “There’s people out there doing that?”

In fact, government oversight of Weights and Measures is as old as the country itself.

Article 1, Section 8 of the Constitution grants Congress authority to “fix the Standard of Weights and Measures.” And Vieira and Oliver both said Governor John Winthrop of the Massachusetts Bay Colony — yes, the “city on a hill” guy — was Boston’s first sealer, in the 17th century.

“Our language is different than anyone else. No one knows about us,” Vieira said. “I feel like sometimes we’re the nerds of a certain world.”

Daniel Kool can be reached at daniel.kool@globe.com. Follow him @dekool01.