SITKA THUNDERHEAD PANTS. The Thunderhead Pants are the perfect extension of the Thunderhead Jacket, featuring GORE-TEX Laminate with a quiet, brushed polyester knit face for ultimate performance. Designed for stalking and ambushing ungulates from ground level in tree-covered and vegetated terrain. Subalpine is optimized for engagement ranges of 50 yards and less. Traditional mimicry patterns based on human vision are designed to look like a specific type of vegetation or terrain. GORE OPTIFADE Concealment is the only scientifically proven concealment pattern based on animal vision to optically fade a hunter into their surroundings. By using advanced blends of micro and macro patterns to fool animal vision rather than mimic a particular shape, GORE OPTIFADE Concealment is more versatile and more effective at getting hunters close to game.