X-Bionic Energizer MK2 Long Sleeve Running Top - SS17 3D-BionicSphere System - Can store more air for insulation. AirComplex-Zone - The system's structure processes excess sweat from physical activity and provides a nice, cool feeling all over. AirConditioning Channel - Ventilation system of channels that flow around the body, continuously carrying away moisture and warmth. Self-adjusting cuff - Keeps the shirt from slipping up or constricting. ExpansionRibs - Allows freedom of movement.