It?s completely Sporadic and I have double checked to make sure it wasn?t my phone because any certified Apple charger I use charges my phone completely fine and I have no problems with them. I like how light weight these are too. As this is my first fluid trainer I don?t quite know how they work internally. The length is 2 inches shorter than 70 inches as advertised. Would definitely recommend now, and if you have adhesive issues, reach out to the seller. I purchased a 2xl and can?t wait to move over a latch ! Having said that, the Jlabs are pretty good once you do the initial pairing. Fit is superb - super comfortable but with no wobble even when shaking my head. Some people might find it too bright. The plastic spines were waay easier to walk around in.