Everyone knows there's a fine line between brave and foolhardy; the trick is to know when you've crossed it.

Sometimes the distinction is obvious. Skiing your first double-diamond slope after a winter of lessons? Brave. Dropping into a Class V rapid when you've never kayaked before? Foolhardy.

How about launching a new hard music format in an era when digital downloads are fast becoming the norm? Before I encountered SanDisk's new slotMusic format, I'd have thought that move foolhardy. Outside the handful of big-name artists you'll find at Wal-Mart or Target, retail outlets for music have practically vanished. And to people of college age or younger, the idea of buying music on a hard format is as foreign as the idea of getting up to change the channel on the TV.

But when you consider SanDisk's strategy, slotMusic starts to make sense. The format uses microSD flash memory cards — a product SanDisk sells by the zillions. So with slotMusic, SanDisk can sell you not only the music and the player as Apple does, but also the microSD cards. Take that, Steve Jobs!

That's all great for SanDisk, but what's in it for you? A lot, actually.

UPSIDES, DOWNSIDES

First off, slotMusic delivers music in higher fidelity than most download services. SanDisk has set the minimum data rate for the MP3 files on the card at 256 kbps, and typically the data rate is 320 kbps. Compare this with 160 kbps for the MP3 files available through Apple's iTunes, or the 256 kbps maximum data rate of the MP3s on Amazon.com. (Download services such as Music Giants and HDtracks do offer music at CD quality or better, though.)

Second, the files are free of digital rights management — something that's not true of the files available through most download services. You can copy slotMusic files from device to device at will. In fact, each slotMusic title comes with a tiny microSD-to-USB adapter that makes it easy to transfer the MP3 files to your computer.

Third, the record company can put extras, such as video clips, still images, extended liner notes, etc. on the microSD card.

Fourth, you're getting a memory card in the deal. You can add more music (typically slotMusic cards are only half full), or — if you decide you don't like the music you bought — erase the card entirely and reuse it. Try that with a CD.

Fifth, you can play slotMusic on most of the millions of cell phones that accept microSD cards.

Sixth, you're buying hard media, so you don't have to worry that you'll lose all your files if your computer's hard drive crashes.

Seventh — and this is the one SanDisk pushes hardest — no computer's necessary to enjoy slotMusic. All you need is one of SanDisk's $19.99 slotMusic players. Shove the card in the player and it just plays.

Of course, slotMusic has its downsides, too.

Each title costs $14.99, compared with $9.99 to download an entire album through iTunes. And you can't buy single songs, just full albums.

Plus, at press time, only 38 titles were available. You've got to give SanDisk credit for getting EMI, Sony/BMG, Universal, and Warner Music on board, but they're going to need 100 times as many titles before they have a real format on their hands. SanDisk won't provide specific information about future releases, but claims it will have many more offerings available by holiday season, and that some slotMusic releases will be "day and date" with the CD releases.

And finally, when you carry the slotMusic player with you, you also have to carry around a bunch of slotMusic cards. An MP3 player with onboard storage holds hundreds or thousands of songs, no cards required.

So there are plenty of compelling reasons to buy slotMusic — and some compelling reasons not to. Only a hands-on trial could get me off the fence.

SAMPLING SLOTMUSIC

SanDisk sent me one of its $34.99 artist-branded slotMusic players, festooned with graphics from Robin Thicke's Something Else album, with the microSD version of the album included in the package. Except for the graphics, it's identical to the standard slotMusic player, and it plays any other slotMusic or microSD cards, not just Robin Thicke.

The company also sent me an additional title, Nelly's Brass Knuckles. The Nelly slotMusic card came in a jewel-case-size pack that included the booklet from the CD, a tiny plastic case for the card, and the microSD-to-USB adapter. Of course, all this packaging largely negates slotMusic's potential for eco-friendliness.

All the advantages SanDisk claims for slotMusic bear out. I was able to play a slotMusic card on my LG enV cell phone, transfer slotMusic files to my computer through the USB adapter, and watch the videos on my computer. I could also transfer MP3s and WMAs from my computer onto the slotMusic card or a standard microSD card and play them in the slotMusic player.

The player itself is OK for what it is. It's a bare-bones model with no display, so you have to keep hitting the track skip and reverse buttons to find the tune you want. At 1.75 ounces with the AAA battery in place, it feels portly compared with my beloved Samsung YP-U3JQG MP3 player/FM radio, which weighs in at a mere 0.6 ounces. The slotMusic Player has no hold switch, but it has something even better: raised edges around the controls. For me, at least, these totally eliminated accidental button punches, and I didn't have to remember to engage a hold switch before I slipped it into my pocket.

THE BOTTOM LINE

For me, slotMusic suffers one giant, unforgivable disadvantage compared with CDs and downloads: I seriously doubt slotMusic will give me the next offerings from Pat Martino, Ornette Coleman, Steve Reich, Rammstein, or any of the other artists I like. But I'm old enough to remember buying Led Zeppelin albums on 8-track, so I've long since moved off the radar of music industry marketing people.

People in the 18-to-34 demographic will be more likely to find titles they like in slotMusic's offerings, but a sparse set of offerings it is. Of course, slotMusic uses a standard digital file format, so there's no risk that five years from now you won't be able to play the music you buy today. But many of slotMusic's benefits will be lost on the youth of today, who don't have a problem using computers and don't have the emotional attachment to hard media we oldsters can't seem to shake.

All that said, slotMusic's kind of neat, but I think SanDisk is totally missing their market. Who would really appreciate having a tiny, ultra-simple portable music player? Retirees, of course. Imagine artist-branded slotMusic players with the likes of Barbra Streisand, Frank Sinatra, Tommy Dorsey, and Perry Como. I guarantee they'd find their way into thousands upon thousands of Christmas stockings in Florida and Arizona. What a great way for record companies to sell all that old catalog stuff one more time. And best of all, imagine not having to waste hours on December 26th teaching your parents how to use the gift you just gave them.