In reply to apa:
They're a slightly restyled, with new shell material, update on the Chugach pant, which were very popular and which I use a lot in Antarctica.
They're much thinner than down pants, so not nearly as warm, but much better to actually climb in, and much less bulky. The shells are a bit thin, so ice screws, axes etc can rip some holes pretty easy. They were originally intended as very warm mid-layers, but putting them under a shell doubles-up on windproof layers and might be too sweaty, unless it's really cold. So I, and most people I know, use them as overpants, where they replace both fleece pants and a windproof shell pant. They are certainly not waterproof. The Chugach seemed to be cut reasonably large, and fairly long, though the Compressors seem to be styled a bit more trimly.
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