Every marketer has to decide how much product to sell and at what price. But few are as fortunate as condom makers, whose customers are glad to pay a premium for a product that isn't much bigger or better.

Consider the Magnum line of plus-size condoms, a sub-brand of industry Trojan. Magnum's share of the market has surged (if you'll excuse the expression) from 4.6 percent of the market in 2001 to 18.8 percent today.

The size of the American male has not seen a similar increase.

"Bigger than most condoms, it is designed to fit those that find normal condoms too constricting," reads one website's copy for Magnum. It closes on the tantalizing note: "These are a little smaller in width and length than the Magnum XLs."

Oh, yes, then there are Magnum XL's. The copy tries to upsell the Trojan customer to Magnum, and the Magnum customer to XL. It's easy to see why men fall for this particular sales pitch. It's also easy to see why Trojan loves Magnums. A box of 12 regular Trojans retails for around $5.99; a box of 12 Magnums or Magnum XLs is $7.99. That's a 33 percent premium. Then there's Magnum Ecstasy, at $10.99 for a box that contains only 10. I doubt that anyone buying a product called "Magnum Ecstasy" does the math, but that's over twice the unit price of the regular Trojans.

Were these gloves instead of love gloves, "small," "medium," and "large" would retail for the same price. So the Magnum premium is pure profit. Furthermore, Trojan has never advertised Magnums. It doesn't have to.

What's not so obvious is the smoke and mirrors behind the Magnum brand. Jim Daniels, vice president of for Trojan, confessed to the New York Times that Magnums are basically the same size, just a little wider in the middle.

The regular Trojan, the Magnum, and the Magnum XL all measure 2 inches wide at the base. The base has to cinch snugly to keep the thing on. There's a slight difference in length. A Trojan Non-Lubricated is 7.8 inches long, vs. 8.12 inches for Magnum. The 0.32-inch difference qualifies as a rounding error in anyone's night of pleasure. As to the Magnum XLs, well, they're 8.12 inches long, too.

The difference is in width of the shaft. Measured at the head, Trojans are 2 inches wide, Magnums are 2.5 inches, and Magnum XL's are 2.75 inches. Well okay, that's a difference. But since all the condoms taper to 2 inches at the base, the Magnums have a rather bizarre shape. It's less a beer can than a very fashionable cocktail shaker of the 1930s.

A rival brand, LifeStyles, has a "King XL" size whose vital statistics are virtually the same as the regular Trojans. There's no policing of the XL designation. And that's probably fine with all parties concerned. This is America, the land where any man can be an XL. All it takes is a little extra cash.