Sony have developed a new sized MemoryStick tentatively called "Duo" measuring just 20 x 31 x 1.6 mm it comes with a detachable cartridge which makes it the same size as a Memory Stick. Developed primarily for the PDA / telephone / portable AV markets. It's purely a develpoment and aimed for production in 2001.

According to this Japanese press release Sony produced 2,000,000 MemorySticks in 1999 and is projected to ship 8,000,000 in 2000 and upwards of 20,000,000 in 2001. They also claim to have the support of 46 companies who have signed usage agreements with Sony.

Basic Specifications of "MemoryStick Duo"