Compact and super light, the Atom SL vest by Arcteryx easily stashes in your pack, ready to grab when summer temperatures drop. The Tyono 20 shell balances breathability and wind resistance, and the Coreloft insulation is light, compressible, and efficient. Lightweight stretch fleece side panels improve ventilation and hold the fit.

So this is a perfect companion that should always have a place in your backpack. 

Features: 
• Moisture-wicking
• Ultralight, compressible and packable
• Wind resistant
• Fleece stretch side panels allow for ventilation
• Trim fit for base layer or light mid-layer use
• Adjustable hem cord seals out drafts
• Two hand pockets with zippers
• DWR finish repels moisture

Fabrics:
Insulation: 100 % polyester
Lining: 100 % polyamide
Side inserts: 93 % polyester, 7 % elastane
Outer fabric: 100 % polyamide