Illinois IHSA Cliff Keen Extra Tall Basketball Referee Shirt . Cliff Keen's MXS shirt extra tall gives you more length in the body and sleeves. IHSA Official embroidered on the left sleeve. Option for the IHSA logo on the left chest. Cliff Keen Athletic is known throughout the world for manufacturing the finest officiating gear you can buy. Cliff Keen's proprietary MXS® Loose Gear Fabric performs great and is moisture-wicking and anti-microbal. Cliff Keen's Loose Gear fabric is light, comfortable, yet plenty durable to stand up to the rigors of multiple seasons. Quite simply, you won't want to ever wear another shirt while officiating.