When you heed the call to get outside, the Merrell Siren Sport delivers comfort, vital traction, and rugged durability with its QForm midsole, Vibram rubber, and protective bumpers. Merrell Q Form Technology Video. QForm triple density EVA midsole for support, cushioning, and stride alignment. Supportive molded nylon arch shank allows forefoot flexibility. Vibram TC5 rubber outsole with 4.5 mm lug depth for traction and grip. Nubuck, pig suede leather, and mesh upper for support and breathability. Air Cushion in the heel absorbs shock and adds stability. Rubber bumpers at toe and heel for protection and durability. Omni Fit lacing system provides a precise, glove like fit. Bellows tongue keeps debris out. Lining treated with Aegis antimicrobial solution to help resist odor. OrthoLite anatomical footbeds add cushion, wick moisture, and inhibit odor. Strobel construction offers flexibility and comfort. QForm Comfort midsole provides women specific stride sequenced cushioning.