Features of the Smartwool Women's Merino 150 Baselayer LS Top Smartwool's lightest weight Merino jerseyfabric Uses a nylon core to increasedurability while still keeping 100%Merino wool next to skin Raglan sleeve design eliminates need for shoulder seams Side seams wrap onto front for enhanced Fit Stretch merrow stitching designed to elevate comfort, range ofmotion, and Fit Fabric Details: 87% Merino Wool / 13% Nylon