SanDisk announced on Thursday at the Photo Marketing Association 2007 (PMA) show in Las Vegas an expansion of its SanDisk Extreme III pro line with a 4-Gigabyte SDHC (SD High Capacity) memory card and a 4-Gigabyte Memory Stick PRO Duo card. Both Sony and SanDisk co-developed the Memory Stick PRO format, and SanDisk manufactures its own Memory Stick PRO Duo cards.

The company also announced on Thursday an 8-gigabyte Ultra II SD High Capacity card, which can store over 4,000 high-resolution pictures or up to 15 hours of MPEG 4 video. The Ultra II SDHC card features write speeds of 9 megabytes per second and read speeds of 10MB/sec.

SanDisk Extreme III 4GB SDHC card has a sequential read/write speed of 20 megabytes per second, while the SanDisk Extreme III 4GB Memory Stick PRO Duo card has a sequential read/write speed of 18 MB per second. Both cards are designed for shooting in extreme temperatures (-13 to 185 degrees Fahrenheit or -25 to 85 degrees Celsius), high altitudes. The 4GB Extreme III card can store more than 2,000 high-resolution pictures or up to 8 hours of MPEG 4 video.

Major camera manufacturers, including Canon, Nikon, Panasonic and Leica, have already shipped or announced a variety of pro-level digital still cameras that use the SDHC format, which is designed to allow for capacities greater than 2GB. Consumer-oriented digital still and video cameras that use standard SDHC cards have been available at retailers since last year. Devices must be SDHC compatible in order to work with SDHC memory cards.

SanDisk’s ultra-portable, MicroMate SDHC Reader, which normally retails for $20 will be bundled with the 4GB SanDisk Extreme III SDHC card at no cost.

Both SanDisk Extreme III SDHC Bundle 4GB + MicroMate USB 2.0 Reader and SanDisk Extreme III MSPD 4 GB are expected to available in April with a suggested retail price of US $139.99 and US $179.99, respectively. The SanDisk 8GB Ultra II SDHC 8GB + MicroMate will be available in June and will retail for US $240.