In the latest attempt to shore up sales of music on physical media, SanDisk and the four major music companies have announced a new format called slotMusic.

SlotMusic will be introduced in mid-October at such retail outlets as Wal-Mart and Best Buy.

Each of these little babies will contain an album, plus extras, on a compact memory card that can be played on mobile phones, PCs and some portable MP3 players. The cards are inserted into vacant slots on phones and other devices. The slots are increasingly common on newer phones, but the placement of the slot depends on the phone model.

SanDisk is a maker of flash data storage card products.

People close to the record companies and retailers said they view the effort as an experiment.

The initial batch of releases will consist of 29 albums, mostly by current pop artists including Rihanna, Ne-Yo, Robin Thicke, New Kids on the Block, Weezer, Usher, Chris Brown, Akon and Leona Lewis. In a nod to older buyers, Elvis Presley is also represented.

The music will be sold in the MP3 format, without digital locks that prevent copying. An adapter will be included allowing users to transfer their music to PCs via their USB slots.

The albums are expected to cost $15 and are likely to be stocked by retailers near CDs and portable devices such as MP3 players and mobile phones. 

More at the Wall Street Journal and TechCrunch.