Correction: An earlier version of this story incorrectly listed the number of people that have signed up for the Penthouse Pool Club. This version has been corrected.

Urban Adventures Cos. is to open its Penthouse Pool Club at 1612 U St. NW on April 1. (Courtesy of Urban Adventure Cos.)

Knockout, a District-based company that makes high-end cotton knickers, won the Harvard Business School Alumni New Venture Competition held at the Pillsbury Winthrop Shaw Pittman law firm in the District last week.

Knockout’s secret is a wicking and odor-absorbing technology that keeps the undergarments from becoming wet and smelly.

Knockout was founded by Angela Newnam, who beat out several other start-ups, including a termite detector, an online brain fitness firm and an online greeting card company.

“The reason we won is that you see a lot of people with interesting ideas, but taking something from concept to actually having customers, retail sales and repeat business ... is the hard part,” said Newnam, 43, whose company has sold more than 20,000 pairs and is in 250 retailers, including such high-end local women’s lingerie stores such as Sylene in Chevy Chase and Georgetown’s Abrielle.

Newnam, a 1996 graduate of the Harvard Business School, said she came up with the idea three years ago. Prices range from $24 to $36 for men’s and women’s underwear and from $50 to $60 for “performance” shirts.

Now she goes to Boston April 23 to compete in the HBS national competition for $50,000 in cash, which “would go straight to our marketing budget.”

Newnam, a former consultant with McKinsey, said she expects tough competition from some software start-ups in Boston.

Factoid of the week

CustomInk, the McLean-based online T-shirt company, served its millionth customer this month.

It also celebrated its 12th birthday. The company, co-founded by Marc Katz, expects to break $100 million in revenue this year.

The company is on a tear with first quarter 2012 up 30 percent over the same period as last year.

Katz, who has 350 employees, said his goal is to push CustomInk’s revenue to $250 million by 2015.

CustomInk is exploring television advertising and is opening a West Coast facility in Reno, Nev., to help make faster deliveries and extend its phone coverage so customers can call into the evening.

So is Katz house-hunting in Nevada?

“No, but I could see spending a lot of time there,” he said.

The Buzz hears:

Venga, the District-based start-up that began last year as a marketing platform for Washington area restaurants, has shifted its business model from customer acquisition to customer retention. Under the new model, Venga harvests every scrap of information on a customer’s bill — server, dishes, amount spent — for use in restaurant loyalty programs, guest satisfaction and micro-targeted marketing. Venga hoovered 20,000 checks and 200,000 data items in one recent 10-day period.

Johnny’s Half Shell, Taberna Del Alabardero, Taylor Gourmet, Ping Pong Dim Sum (Dupont and Chinatown), Café Bonaparte, Napoleon Bistro & Lounge, Stir Food Group (Zola, Zola Wine & Kitchen, Potenza) and Spike Mendelsohn’s Good Stuff Eatery and We, The Pizza have all signed up.

Washington Post Publisher Katharine Weymouth and BET Holdings Chairman Debra Lee plan to host separate sessions on May 7 kicking off a new leadership series sponsored by The Economic Club of Washington, D.C. The programs, hosted in board rooms, are designed to provide groups of 25 or so Economic Club members with the opportunity to gain more in-depth knowledge about local businesses.

Other meetings will be hosted by Economic Club President David Rubenstein, one of three co-founders of The Carlyle Group, the private equity giant based in Washington; Kathleen Matthews, executive vice president of global communications and public affairs for Marriott International; and Carol Melton, executive vice president for global public policy at Time Warner. Dates will be forthcoming.

David von Storch’s Urban Adventures Cos. opens its Penthouse Pool Club at 1612 U St. NW on April 1. The $2 million, 12,000-square-foot rooftop area includes a 60-foot pool, private sun deck carpeted with synthetic grass, 10 cabanas, a VIP cabana, communal fire pits and a lounge offering full food and beverage.

Some 1,000 people have already joined with 200 on the waiting list. Monthly membership costs $199 a month, which includes access to all five D.C.-area Vida Fitness locations; the VIP cabana is $500 a day with a food and beverage minimum.

Bethesda-based KoolSpan, which develops encryption chips for mobile communications devices, signed a big European carrier.