Irwin, who is still at age 57 the dominate force on the Champions Tour, will be outfitted with the company's hat, bag and play TaylorMade's rac LT sticks.
Irwin and Clarke will both use the R510, the company's wildly popular driver.
Clarke, still a major presence on the European Tour and ranked 27th in the world, will play the company's rac prototype irons, as well as wear the their hat and his caddie carry the company's tour bag.
Irwin led the Champions Tour in money earnings in 2002 and tied Bob Gilder for the most wins with four. His 36 career wins on the Champions Tour is seven more than runner-up Lee Trevino's 29.
Clarke has nine official European Tour wins to his credit and has won at least one event in each of the past five seasons.