It's a paradox of modern times: As more transactions can be handled electronically, with neither cash nor paper nor plastic, our wallets are bursting with all three - literally.

Experts in the wallet trade argue that the best-selling styles for both men and women are the most inconvenient and inefficient.Men, they say, should be carrying bifold wallets (trifolds are woefully unhip). And women should trade in 7-inch checkbook-change-purse combinations for several smaller pieces that can be tucked into an evening bag.

According to Jeff Frank, regional sales vice president for Bosca, one of the oldest wallet manufacturers in the United States, thinner means longer and wider means thinner.

A thinner wallet puts less strain on stitching and other vulnerable wallet parts that may crack or burst. And a wider wallet spreads the wallet contents over a larger area, making it thinner.

For men, that means a bifold wallet.

But most young men start out buying trifolds because of their narrow profile - and because they have little to carry besides a driver's license and date money. As they get older, the old trifold begins to take the shape of a jumbo bar of soap.

Women, too, stubbornly cling to their traditional 7-inch wallets even though two or three separate leather accessories can be split up among jacket pockets, fit better into a purse and can be cheaper, depending on the style.

A checkbook cover, wallet with change purse and credit card holder from Bosca cost about $90, compared with $117 for a 7-inch frame.

At $60, Bosca's basic bifold is in the middle of the market. At the low end, Buxton can put a leather wallet in your pocket for $21.

With proper care a wallet can last as long as three to four years.