I feel very comfortable leaving my new bike locked up while I shop or hike. The vibrations send sound to your ears, allowing you to experience full audio as well as keeping in full tune with your surroundings. Also, if you by the unlocked models from amazon then you get Alexa built in. I realized THAT is what the music was coming out of! My only issue is that I think its a little cheaply made. Cheap Pakistan knock off not worth 5 bucks or my time! I have high arches and other foot problems but my gripe with my Birkenstocks is they?re way too heavy. Calzo del 28. The indicator of wear to me is how the sole is wearing beneath the ball of my foot. Right out of the box, I couldnt get the left and right to pair.