IK Multimedia iRig Keys I/O 25 MIDI Keyboard Controller ※This is a junk item. The keys from F above middle C are not working. The keys can be used for one octave without any problems, so I have been told that it can be used for recording if you use the transpose button. Also, as with other iRig Keys I/O models, I confirmed that it doesn't power on with an old iPhone (X) unless it has external power, and it works when using batteries or an AC adapter. I haven't confirmed this on all OS versions, so the phenomenon may vary depending on the usage environment. I'm not good with machines, so it might be a setting issue. I don't know if it's a specification. → It was a specification. ・Supplementary quote 【IOS: When connecting to an IOS device, you need to use either AA batteries or a power adapter. When connected with a power adapter, the IOS device will also be powered. Also, when both batteries and a power adapter are installed, the power adapter will always be prioritized.】 During the operation check, I connected earphones to the keyboard itself and confirmed that only the notes below F above middle C could be heard. I haven't checked anything else. (※I've forgotten how to use it, and I can't check it by switching to an iPhone.) Included items: Items shown in the image (Lightning cable, stand) This is a model that integrates a 25-key MIDI keyboard and an audio interface. ※This is a junk item. Please purchase only if you understand this. 【Brand】IK Multimedia 【Product Name】iRig Keys I/O 25 【Product Condition】Junk item 【Color】White 【Other】25 keys, built-in audio interface Thank you.