Under Armour Junior HeatGear Sonic 4 Inch Running Shorts - Medium - Black HeatGear Sonic Fabric - Yields comfortable, consistent support in the lightest possible format. Signature Moisture Transport System - Wicks excess sweat away from the body. 4-Way Stretch Fabrication - Permits a full range of motion and unimpeded comfort whilst retaining shape and structural integrity. Anti-Microbial Technology - Quells the spread of odour-propagating bacteria. Flat, Elasticated Waistband - Sits comfortably against the hips for an accommodating, agreeable fit.