Used a few times. The AIAIAI/Tracks are portable headphones featuring a dynamic sound created by a tight bass and detailed high frequencies from the 40mm driver unit. They have a unique design with an adjustable mechanism that slides the earcups for adjustment. ＜Features＞ ・The aluminum headband is flexible, lightweight, and fits comfortably on the ears. ・The earcups are detachable and can be stored compactly. ・You can customize the headphones using the included sliders (black and yellow). ・The design is by kibisi, a design unit from Northern Europe that is currently attracting the most attention, including designing the Danish Pavilion at the Shanghai World Expo. ・Tracks is a headphone that won the prestigious design award, Creative Circle 2012. ・Tangle-resistant integrated Y-connector ・Lightweight, soft cable ・The open-cell pads are durable, flexible, and easy to use and comfortable. ＜Specifications＞ ・Headphones ・Driver Unit: 40mm ・Impedance: 32Ω ・Sensitivity: 112dB +/- 3db ・Frequency Response: 20～20,000Hz ・Maximum Input: 40mW —————————————————