That Big 'H' on your roommate's sweater doesn't mean he's from Hackensack, N.J., rather it most likely stands for an even more august and tradition-laden institution.

As college insignia products have become increasingly popular in recent years, they have turned into big ticket items for college stores, where they now account account for 20 to 30 percent of all sales.

Managers and salesman at the Harvard Coop and at the collegiate supermarkets of Columbia, Brown, Wellesley, Stanford, and others, say this is due to today's conservative youth who buy more traditional products.

Students in the eighties are more traditional and college-oriented than those of the sixties and seventies, said Thomas W. Bauer, general manager of Columbia's bookstore. He said today's students are eager to show off school pride with insignia shirts.

"Ten years ago, you just couldn't sell something with the school's name on it. Within the last ten years it's just escalated," said Thomas J. Fitzgerald, a buyer for the Barnes and Noble bookstore that serves Tufts University.

Bear Wear

Another contributor to increased sales has been the expansion of insignia product lines. UCLA's "Bearwear" department stocks 30 different T-shirts and 15 different sweatshirts, said an official at the store.

When a particular item sells well, it often sells phenomenally well. Sales of heavyweight "reverse weave" University of Michigan sweatshirts, which were recently introduced at Ulrich's Books in Ann Arbor, have gone through the roof.

"When you get 16 dozen of an item and it's gone in three days, you know you're making money," said David B. DiLiscia, a salesman at the store.

Prestige plays a primary role in the sales of a few big name insignia products like those of Harvard, Princeton, and Stanford.

Visitors to the Boston area seek out Harvard sweatshirts as ideal souvenirs, said Sandy M. Pochapin, sales promotion director for the Coop.

Tourists to New Jersey have a similar aim. "Everybody wants to have a sweatshirt or a T-shirt that says 'Princeton'," Princeton Store buyer David I. Antis said.

But its not just the ancient eight which make a profit from peddling their name.

Insignia items are even more popular at smaller schools, said Christine O'Brian, assistant merchandise manager of Brennan College Service, which manages many college stores in the Northeast. She said students at large schools do not feel as much allegiance to their alma maters as their small college counterparts.

While traditional sweatshirts are undoubtably the most popular insignia item--sweats make up 40 percent of all Stanford insignia sales--many unusual items have been emblazoned with college emblems.

Williams College toilet seats are a hot item on that campus. Ulrich's in Ann Arbor carries school toilet seats and also "Michigan Musical Mugs," which play the school fight song when lifted. UCLA sells authentic "Bruin" tambourines and the Coop offers a handmade hat and coat ensemble for the future graduate of Harvard Dog School.