A ridiculous number of accessories are available for Apple devices. If you have an old iPhone 3G, you'll have no trouble finding an array of compatible docks, cases, covers and speakers. No so with another three year-old phone like the HTC Treo Pro. Even with this wealth of iPhone options, the Sony RDP-M15iP is a little out of the ordinary. It's a fairly big iPhone dock that comes with a great big battery to let you use it out and about for long periods.
The Sony RDP-M15iP is an odd clash of ideas. Its 35cm width and inclusion of two drivers for proper stereo imaging suggests it's a full size home dock, but it's actually something else. It has been designed with portability in mind, as it's surprisingly compact and has a built-in rechargeable battery that lasts for up to 6 hours.
Aside from the battery pack, two retractable elements make this dock really work as a portable solution. A back stabiliser folds back into the RDP-M15iP's body and the dock mechanism can be pushed back into the body with the aid of a button on its front. It retracts back in with a silky smooth motion that's pure Sony - dead stylish.
With these two elements put away, the RDP-M15iP is a solid rectangular bar of metal and plastic that'll fit very happily into a bag. It's not small but is rucksack-friendly. A fabric case - like a black drawstring Christmas stocking - is included in the box to avoid scratches. The front speaker grille is metal, the rest of the body plastic, and it's hardy enough to endure a life of occasional bumps and scrapes.
There's a standard AC socket to charge the battery or use this gadget as a home dock, and the only other port is a 3.5mm auxiliary input alongside it. This lets you input other sources, such as a smartphone via the headphone output or, if you want to go retro, a discman.
A simple remote control is included, letting you navigate through an iPod's music library, change tracks and alter volume, but there are on-body controls available too. Buttons along the top of the RDP-M15iP turn the dock on and off, play/pause, alter volume and select from the three main sound settings - which can be roughly described as "normal", "extra bassy" and "extra trebly".
It's a slightly perfunctory-looking dock, but you start to appreciate its simple look once you consider how much a benefit this is to its portability. Any frills to deviate from its slanted rectangular blockiness might also reduce its strength.
The Sony RDP-M15iP does offer one extra bit of functionality though - you can swivel the iPhone dock arm so that it sits in landscape orientation. This comes in very handy for watching movies on that iPhone diddy screen, or if you want to use the dock as a sort of alarm clock.