Id say mainly due to how well the rubber holds traction with my phone i say this as i dont leave the charger on the side but have it on the sofa so it does manage to sit at some good angles and keep the phone firmly in placethe ring will light green once it begins charging your phone so at a glance you can tell its charging appreciated as my phone wont charge properly via cable and often disconnects

Really good use a good usb charger for high speed charging works well on iphone 8 i have to say im quite pleased with this charger