Atom Series: Insulated mid layers made with hydrophobic synthetic material that resists absorbing moisture. Outer fabric has a water-repellent finish. LT: Light Weight. Built with highly durable top performance materials but designed with streamlined minimalist set of features to provide very light weight. CUSTOMER SERVICE TIPS Arc teryx Atom LT products have non-locking zippers by design. One purpose of the non-locking zipper is that it is easier to operate with one hand. This design feature also helps to limit the possibility of damage to the zipper and lightweight face fabric directly adjacent to the zipper. This sleeveless core-heater hugs the body with efficient Coreloft(TM) insulation to preserve warmth while durable fleece side panels-made with Polartec(R) Power Stretch(R) with Hardface(R) Technology-increase active use breathability and mobility. A wind and moisture resistant outer shell extends stand-alone usability. Features: Moisture-resistant outer face fabric Breathable Insulated Lightweight Compressible and packable Wind resistant DWR finish (Durable Water Repellent) helps repel water from fabric surface Composite construction Breathable, stretch side panels for enhanced comfort and mobility Soft, smooth lined collar Full front zip with wind flap Stretch-knit cuffs Laminated hem Drop back hem Internal chest pocket Two hand pockets Trim Fit Weight: 220 g / 7.8 oz Activity: Ski/Snowboard / Ice Climbing / Alpine Climbing / Hiking / Trekking Materials: Polartec(R) Power Stretch(R) with Hardface(R) Technology-88% polyester, 12% elastane, 230 g/m . A four-way stretch fabric that allows for excellent athletic movement and good breathability to maintain comfort. Some products feature Hardface(R) Technology for a higher level of abrasion resistance. Coreloft(TM) 60 (60 g/m ) insulation. Made with highly crimped multi-denier siliconized polyester yarn, this lightweight, breathable, and thermally efficient, 100% polyester staple fibre is very compressible and has excellent loft retention. Tyono(TM) 20 denier shell with DWR treatment - 100% nylon