The arkon SM-WRIST forearm support is a great alternative to standard armbands (I prefer to think of it as this rather than a wrist holder as thats where it seems to sit on my arm) Quickly applied to your forarm you can be off on your run immediately and because of its position it is easy to see the screen and make and required to changes to your running app or music whilst running. The case is compatible with standard size smart phones such as the Apple iPhone 4 4S, Blackberry 9900, Orange San Diego [SM-WRIST] Sports Arm Holder for iPhone and Smartphones up to 4" Arkon's SM-WRIST fits all iPhone models and most Smartphones having up to 4" screen size. Features a neoprene sleeve with reflective safety strips sewn into the fabric, touch-through window and velcro adjustment strap. Designed to fit phones with screen size up to 4" Made of stretchable, sweat resistant neoprene material Lightweight design includes storage pouch for money or other essentials on the go Clear plastic cover enables operation of phone's screen, while in the armband pouch Cutouts and slit for audio jack on top and bottom Works with some cases. We have found that if your case has a smooth surface and doesnt add too much bult then it should be fine. However a gel style case which has quite some grip may be difficult to insert.