Details Arc'teryx Men's Size Chart One of the most versatile fleece jackets Arc’teryx has ever designed, the Delta LT provides effective warmth with little weight. Quick drying, air permeable Polartec® Classic 100 micro velour small grid and articulated construction focused on ergonomic freedom and performance comfort make the Delta LT extremely versatile. The Delta LT layers easily under a hardshell, but as a standalone adds light insulation for higher output in cool conditions. The design is a longer and slightly more relaxed trim fit. A low profile ScubaHood™ adds more warmth and fits under a helmet.