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This is s a perfect option to show off both your website and your app mockup in one stage. At the top you get an black apple iPad in portrait mode that will display a 768x1024px image. Below that you have a grey iPhone 5s set to landscape view that allows for an 1136x640px image. These are set at a music studio with music equipment around it. A great backdrop for sound mixing or any music related apps.
Drag & drop not supported, but you can still upload via this input field: