THERE was a time, before the advent of fanny packs, messenger bags and the man-purse, when you knew what a wallet stood for.
In the 1960's my father's scuffed brown leather wallet contained all the important things a man needed to navigate the world: cash, his driver's license and a claim check to retrieve the radio from the repair store.
A stuffed leather wallet, left, and the Slimmy, one of the thinnest available.
Then credit cards took over the world. Nowadays a wallet is a beast of burden, swollen with Visa, MasterCard, American Express and Discover, not to mention cards for automated teller machines, insurance plans and employee ID scanners. Put one of those bloated wallets into a back pocket, sit on it, and you will look like my husband. One of his shoulders is about two inches higher than the other. "Have you seen my glasses?" he asked the other night.
"They're next to you on the table," I said.
Slowly, he swiveled the entire top half of his body until the eyeglasses came into view. As his fingers closed around them, he winced. He looked as creaky as the Tin Man headed to Oz.
"Should I get the oil can?" I asked.
"Neck hurts," he said, careful not to move his lips.
It wouldn't take a genius to suspect a connection between his neck problems and his wallet. My hunch was confirmed by a spokesman for the American Chiropractic Association, who said fat wallets - already notorious for causing the leg and lower back pain known as sciatica - are bad news for the whole musculoskeletal system. "Does your husband sit for a long time on his wallet?" asked Dr. Jerome F. McAndrews, the national spokesman for the association.
"All day," I said.
"Then it's possible his neck pain is related to the wallet," Dr. McAndrews said. "The minute you force one side of the pelvis forward from having that thick wallet in a pocket, you are rotating virtually every vertebra in the spine. The vertebrae above compensate for the rotation so that he can sit up straight instead of leaning over like the Tower of Pisa."
"He does lean," I said.
"He could have vertebrae rotated all the way up the neck, and could have effects anywhere along the way," Dr. McAndrews said.
The best cure I could think of was to go online to buy something more neck-friendly than the typical department store wallet. But what? My husband is a traditionalist. Not for him the camouflage big-shoulder messenger bag ($42) from ebags.com or the lightweight Hawaiian surf print wallet ($4.97) at maikaihawaii.com. Nor could I picture him carrying a shiny, quilted day bag like the one listed in zappos.com's "Men's Accessories" category ($65.95), not even if its red color was described as a manly "chili pepper."
"Brown," he said, economizing on verbs to avert pain. "Or black."
"I found a nice black nylon man-bag for $40," I said, showing him a printout from the man-n-bag.com. "It has a pocket for gadgets and a key chain docking clip." "Shoulder strap?" he asked suspiciously.
"Yes," I admitted.
"It's a murse," he said, using the man-purse's nickname to avoid a second syllable. "No."
"The site's F.A.Q. says there's no such thing as a man-purse," I read aloud. "
'Man-purse is an oxymoron.'
"Need wallet that probably doesn't exist," he said. "Impossibly thin but also able to hold everything. Yet must flatten like pancake when I sit."
Inspired by this vision of a superhero wallet, I did a Google keyword search for "world's thinnest wallet." The next morning I was on the phone with Cindy Whitehawk, the co-owner of the nobulges.com. Displayed on the site were photos of a beefy leather wallet alongside her company's wafer-thin All-Ett, made of rip-stop nylon, with a "patented side-by-side design that creates four pockets for cards."
"Those photos are powerful," I told Ms. Whitehawk.
"My husband, Ken Obenski, is an engineer, and he invented the All-Ett after he had sciatica problems," Ms. Whitehawk said.
"Before we took it to market, we had them in a hundred guys' pockets for six months to test and get feedback."
The All-Ett, which Ms. Whitehawk said was as thin as a dime, unfolds to reveal two panels, each of which snugly holds two stacks of credit cards (up to 30). It comes in seven colors - including black but not brown - and costs $14.95. When I asked Ms. Whitehawk about competitors, she scoffed. "There's one made of leather that claims to be the thinnest," she said. "But leather? Right there, a piece of leather is 10 times thicker."
I ordered an All-Ett in traditional black (the cost was $18.16, including tax and ground shipping). While awaiting the mail, I decided to investigate a leather competitor - called the Slimmy - which comes in both black and brown, costs $29, claims to be "the world's slimmest wallet" and is sold exclusively online at sites like koyono.com and amazon.com.
Jay Yoo, president of Koyono, said: "We haven't found anything slimmer. Have we checked it against every wallet in the world? If I had that kind of time, that would be a great thing to do."
Mr. Yoo mailed me a review model.
I lined up the competitors directly in my husband's line of vision. The Slimmy was slightly fatter - maybe a dime's worth - and looked more like a business-card holder with multiple sleeves than a full-fledged wallet.
I watched my husband load the contents from his old wallet into each. The Slimmy could hold only 10 cards before they started to slip out into his back pocket (a problem that disappeared after he moved the wallet to a front pocket on the advice of Mr. Yoo). The All-Ett comfortably held all 23 of his cards and had room for more. Both were less than half an inch thick and, when pocketed, were far more comfortable than the old, bulky wallet.
During a sit-down test, the All-Ett's rip-stop nylon made a crinkling noise, which my husband said sounded as if "I'm wearing diapers."
Two days later, however, he said he had grown fond of the crinkling. "It's so thin that otherwise I wouldn't know it was in my pocket," he said.