Few people would think to improve on something as basic as the safety pin, but entrepreneur Pete Roberts has done the equivalent, twice, with the lowly wrench. The first time was in 1963, when Roberts, then an 18-year-old stock clerk for Sears Roebuck, developed a quick-release mechanism for ratchet wrenches that enabled users to change sockets with one hand.

While Roberts's quick-release feature was the first significant change to ratchet wrenches in living memory, it wasn't perfect. Scraped knuckles, cut or burned hands, and ratchet wrenches that came apart from a socket under pressure were still daily hazards for wrench wielders. That is where Roberts spotted opportunity for wrench improvement number two. In 1993, with his lawyer, John Davidson, as a partner, Roberts launched Link Industries in Chicago and introduced the Link Dynamo. That wrench, he claims, keeps the hand farther from the work area and thus more protected, and will not come apart even when intense pressure is applied. "With the ratchet wrench I got to the 50-yard line," says Roberts. "It was still incomplete."

After battling (and finally winning) a 20-year lawsuit against Sears over patent rights to his original quick-release invention, Roberts is currently eschewing big retailers and is selling the Link Dynamo directly by advertising on infomercials, in trade magazines, and with inserts in credit-card mailings, including Mobil's. Davidson, Link's president, is cagey about making projections in an industry with fewer than 20 significant players but says the start-up anticipates capturing a 10% to 15% share of the existing $1.7-billion wrench and hand-tools market within five years.

-- Alessandra Bianchi