This Incendo Pant from Arc'teryx is their lightest weight softshell pant.  Perfect as the next thing to throw on when wearing shorts just isn't enough.  These pants are made from a lightweight 4-way stretch woven nylon blend fabric.  Great for slightly cool approach hikes, scrambles, and trail running. 
Details
- Super Lightweight Fortius™ Air 50  4-Way Stretch Woven Plain Weave Softshell Fabric, 84% Nylon / 16% Elastane
 - FC0 DWR Durable Water Repellent Finish
 - Low-Profile Elasticized Waistband
 - 2 Open Hand Pockets
 - Internal Mesh Pocket
 - Gusseted Crotch
 - Articulated Patterning
 - Regular Fit
 - Ultra Lightweight
 - Extremely Breathable
 - Stretchy
 - 6.5 oz (185 g)