The Rho Heavyweight – our warmest base layer pant – is made for cold days and mixed output. On the move, the Polartec® Power Stretch® Pro stretches for outstanding freedom of movement. During rest phases – or when it gets really cold – the fleece’s soft brushed interior traps heat to keep you warm. The fleece’s durable nylon outer has a smooth face for comfort under layers, and a zippered thigh pocket secures small essentials.  The Rho Heavyweight Bottom was previously the Rho AR Bottom.