The X-speed ratings are a way for Kingston to help consumers rate the speed of a storage card similar to the way CD and DVD drives are rated based on their X-speed.

The new SD card from Kingston Technology.

Since this is a Kingston only initiative, we’ll spell it out. The SD Ultimate cards have a read rate of 23MBps and a write rate of 20MB/sec. The latter is where it gets the 133X rating. X = 150 KBps.
However, the speed will actually vary depending on the host hardware, software and usage. You can get more info on the speed ratings here.

“Kingston developed the SD Ultimate line to give serious and professional digital enthusiasts a greater array of choices for their digital media,” said Keith Hamilton, Regional Manager, Kingston Technology. “Our SD Ultimate cards provide superior performance to help users optimize their high-end digital equipment, whether a digital camera, MP3 player or PDA,” he added.

The cards are priced $139 for the 512MB (RRP) and $299 for the 1GB (RRP). They are available from Simms International, Ingram Micro and Synnex.

The company also plans to offer a high speed Compact Flash line under the Ultimate brand.