Photon PantsRab USA
The Photon Pants are an exceptionally warm and highly durable insulated pant, designed to provide warmth and greater freedom of movement in extreme mountain environments.
Reinforced knees and seat and kick patches add durability in high wear areas. The full-length side zips make the pants easy to take on and off when wearing mountaineering boots and even over crampons. An expedition fit means the Photon Pants can be worn as an outer layer in even the harshest environments.
Here's further information on why you (might) need insulated pants.
Weight: 1lb 3oz / 530g