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Helly Hansen says:
Our 2-layer system enables maximum moisture management while keeping you warm all season long.
LIFA® ACTIVE is a performance base layer, delivering superior moisture management and lightweight insulation for all year activities. LIFA® ACTIVE is an advanced two layer construction with 100% LIFA® fiber next to skin and wicking technical fibers outside. All in all, an unbeatable combination for moisture management, lightweight warmth and all day comfort.