Hosa MHE-158 3.5 mm TRRS to Slim 3.5 mm TRRS Headphone Adaptor Slim TRRS adaptor designed to connect standard and microphone-equipped headphones to smartphones with protective cases that prevent connection of full sized plugs Provides a secure connection through most phone cases, especially those that include external batteries, like Mophie cases Allows you to continue to using your current headphones by adapting them to the slim connector format, rather than having to purchase new ones with a slimmer connector 3.5 mm TRRS to Slim 3.5 mm TRRS