Review: Solution to the unknown problem

File these under "solutions to problems you didn't know you had."

They're the SanDisk Connect Wireless Flash Drive and Wireless Media Drive, two new gadgets that provide on-the-go solid-state storage for, and access to, movies, music, photos and documents. They're unobtrusive, modestly priced and ridiculously useful.

Why would you want something like this? Maybe to take a few movies along on a trip without eating up the storage space on your phone or tablet. Maybe to stream a multimedia presentation to several users at once.

Or maybe it's just to keep a couple of kids in the backseat amused.

With battery life of up to eight hours, the drives could make long car trips a lot quieter.

The concept of Wi-Fi-based mobile storage isn't new. Most such products, like Seagate's GoFlex Satellite, use mechanical hard drives to store your content. The SanDisk devices, by contrast, use chips.

Each approach has advantages. Hard-disk-based drives can hold much more and are cheaper on a per-gigabyte basis. The SanDisk drives are smaller, lighter, cost less out of pocket, use less power, and, since there aren't any moving parts, don't run the risk of a mechanical failure.

The flash and media drives work similarly but come in different capacities and forms.

The Flash Drive looks and works like a slightly overgrown thumb drive. A tiny hatch covers a slot that houses the removable memory card.

It costs $50 for a version with a 16-gigabyte card -- enough for seven or so standard-definition movies -- and $60 for 32 GB.

The Media Drive, meanwhile, is a palm-sized square that's about 2.5 inches on each side and weighs 2.5 ounces.

It costs $80 for 32 GB and $100 for 64 GB.

Both use a computer's USB port for downloading content and recharging, and can connect to up to eight mobile devices at a range of up to 150 feet. But the Media Drive has a beefier battery; the Flash Drive's maximum is four hours, and less if you're streaming to multiple devices.