Teresa Knaus always carries a knife. But it's no ordinary pocket knife.

It's a Swiss army knife, that remarkable gadget sometimes equipped with as many as 30 miniature tools for a multitude of uses.The knife isn't new, having been invented by a Swiss, Karl Elsener, in 1897. But it's seen many variations through the years. Some people wouldn't be without one - or more.

"I use it all the time,' said Mrs. Knaus. "I cut a piece of cheese or an apple in the car, or open a bottle with the corkscrew. I used the Phillips head screwdriver not long ago to tighten the handle on the car door."

Her son, Dan, gave her one several years ago. She, in turn, gave one to Misty Simpson, a friend of her daughter, Lynne, who also owns one. "They go camping a lot together and have many uses for them," she said.

"I've noticed that women are buying them for themselves more and more," said Memphis, Tenn., store manager Debra Kirkpatrick. "Women mainly like the ones with scissors. A lot of women who go camping or garden find tools on them they can use."

She owns a model of the Victorinox Swiss army knife called Super Tinker. It has a pair of scissors, a Phillips head, leather punch and two regular blades.

"I clip coupons with the scissors, and use the screwdriver constantly at work," she said. "I make holes in belts with the leather punch."

Her store carries 25 models of the Victorinox, ranging in price from $9 to $90.

"The Swiss army knife has always been one of our biggest sellers," said Ms. Kirkpatrick. Most of them have a corkscrew, leather punch, Phillips head, file blade, scissors and one or two regular blades.

"The newer ones have pliers, and the newest model we have, the Swiss Champ, has a little ballpoint pen," she said. "They've also come out with a new one that has a lock blade."

Ms. Kirkpatrick sells anywhere from 25 to 50 Swiss army knives a month. "It varies," she said. "Someone might buy 10 at a time for groomsmen's gifts or for business clients. We have several businessmen who have bought numbers of them two or three years in a row for gifts. And we sell quite a few at Valentine's since most of them are red."

Brookstone, a company with headquarters in Peterboro, N.H., carries several models in its stores and catalog, said Charles Gibbons of the customer service department.

"The Survival Tool Kit has 38 parts," he said. They include large and small blades, a compass, corkscrew, needles and thread, pliers, a ballpoint pen, mechanical pencil, file, fish line, can opener, small saw, bottle opener, screwdrivers, scissors, magnifying lens, a six-inch ruler, bandages and other parts. It costs $100.

"The one I would consider for women is the Classic, which is a much smaller version than the others," said Gibbons. "Women can carry it easily in a purse." It has three blades, plus a toothpick and tweezers.

Judy Snodgrass of Sharper Image said her store just put the Victorinox Swiss army knife in its February catalog. Priced at $75, the knife has various size blades, a rope saw, can and bottle openers, nail file, tweezers, a toothpick, three flat-head and one Phillips head screwdriver, a wire stripper, an awl, scissors, a metal file, metal saw, wire cutter that also can be used as a wood chisel and a pair of pliers.

Ms. Kirkpatrick said she doesn't know why the Swiss army knife is traditionally red. Some of the newer models come in black and white. "The Little Classic, which is good for attaching to a key ring, comes in a variety of colors," she said.

Nancy DeFeo's Swiss army knife saved the life of a colt about 14 years ago in Iowa.

"I was driving to a farm where I kept my horse when I saw a colt about a week or two old that had caught his harness on a fence post and couldn't get it off," she said. "He was really struggling in a panic. I honked my horn but couldn't arouse anyone. Then I remembered my Swiss army knife and got out and cut him loose." She got a cracked rib in the process. "But if I hadn't had that knife he would have died," she said.

Since that time she has made a point to have the knife in her pocketbook at all times, she said.

"When my purse was stolen, the first thing I did was go out and buy another Swiss army knife. I wouldn't go anywhere without it."