What is the SD Speed Class?
The SD Association has established specifications that rate the minimum data transfer in SD, SDHC, SDXC, SDHC UHS-I and SDXC UHS-I memory cards and host products. The speed rate specifications were established based on the needs of movie and video companies. Video recording requires certain writing speeds when recording the data onto an SD card. The SD Speed Class and UHS Speed Class standardized the specification for both card and host devices in order to guarantee minimum writing speeds.
What are the applications for Speed Class?
a. Class 2 : H.264 video recording, MPEG-4, MPEG-2 video recording
b. Class 4: MEPG-2 (HDTV) video recording, DSC consecutive shooting
c. Class 6: Mega-pixel DSC consecutive shooting, professional video camera
d. Class 10: Full HD video recording, HD still consecutive shooting
e. UHS Speed Class 1: real-time video recording on video cameras and digital cameras
What is UHS/UHS-I/UHS-II?
Ultra High Speed (UHS) defines bus-interface speeds up to 104 Megabytes per second for UHS-I and up to 312 Megabytes per second for UHS-II. Bus speeds power data transfer speeds between SD host devices and SD memory cards. UHS is exclusive to SDHC and SDXC memory cards.
What is "SDXC"?
SD Extended Capacity (SDXC™) card is an SD™ memory card based on the SDA 3.0 specification. This new SDA 3.0 specification enables SD cards to reach higher capacities: 32GB up to 2TB. Because SDXC uses a different file system called "exFAT" and it works differently then standard SD cards, this new format is NOT backwards compatible with host devices that only take SD (128MB to 2GB) or SDHC (4GB to 32GB) cards. To ensure compatibility, look for the SDXC logo on cards and host devices (cameras, camcorders, etc.).
SDXC cards and host devices
- SDXC memory cards can ONLY be used with SDXC host devices.
- SDXC memory cards will NOT work with SD / SDHC host devices.
Additional info on SDXC cards and host devices
- SDXC host devices can use and support SD, SDHC and SDXC memory cards.
- SDHC host devices can use and support both SD and SDHC memory cards.
- SDHC memory cards can be used with SDHC and SDXC host devices.
What operating systems support the exFAT file format?
Operating System
exFAT support
Patch download
Windows 7
Supported natively
Windows Vista
Requires update to Service Pack 1 or 2
(both supports exFAT)
Download Service Pack 1 (with exFAT support)
Download Service Pack 2 (with exFAT support)
Windows XP
(Service Pack 2 or 3)
Requires exFAT patch update
Must have Service Pack 2 or 3 installed to use this update
Download exFAT patch update
Mac OS X
Requires Mac OS X version 10.6.6 and above
Why can't my computer (with internal card reader) read my 4GB or higher SDHC card? My digital camera can't read my 4GB SDHC card as well. What do I do?
SD and SDHC compliance
If your computer's internal card reader works with 2GB (or lower) SD cards but fails to read a 4GB (or higher) SDHC card, then the computer's internal reader is not SDHC compliant.
This same logic also applies to digital cameras, if the digital camera reads 2GB (or lower) SD cards but fails to read a 4GB (or higher) SDHC card, then the digital camera is not SDHC compliant.
SD and SDHC specifications
The initial SD card specification defined the interface for cards only up to 2GB capacity. The subsequent SDHC specification was developed to provide increased capacity of 4GB – 32GB cards. Computers and other products purchased before 2008 may not be SDHC compatible. Computers and other products purchased before 2007 are not SDHC compatible.
Verifying the card reader slot
If the card reader slot on your computer does not have the SDHC logo, it is most likely not SDHC compatible and will only read cards up to 2GB capacity.
Other options you can use to read files on your SDHC card
If your computer's card reader is not SDHC compatible, you have 3 options available:
1. You can connect your camera (or other device) that works with SDHC to your computer using a USB cable that came with the camera. You should be able to transfer files to the computer this way.
2. You can contact your computer manufacturer to see if they have a free firmware update for your model that will make it SDHC compatible
3. You can buy an inexpensive SDHC card reader that will connect to your computer's USB port.
8) What is "SDHC"?
SD High Capacity (SDHC™) card is an SD™ memory card based on the SDA 2.0 specification. This new SDA 2.0 specification enables SD cards to reach higher capacities: 4GB and higher. An SDHC capacity goes from 4GB to 32GB and SD goes from 128MB to 2GB only. Because SDHC works differently than standard SD cards, this new format is NOT backwards compatible with host devices that only take SD (128MB - 2GB) cards. To ensure compatibility, look for the SDHC logo on cards and host devices (cameras, camcorders, etc.)
Why do I get a "The disk is write-protected" message when I transfer files to my memory card?
Unlock the memory card. There is a Lock switch on the left side of the SD card. Make sure the Lock switch is slid up (unlock position). You will not be able to modify or delete the contents on the memory card if it is locked.
NOTE: If you are using a microSD/microSDHC card or a miniSD/miniSDHC card, insert the card into the standard SD adapter.
If the lock switch is not on lock: Toggle the lock switch.
1. Slide the switch up and down. Repeat this 3 times.
2. Let it stay on the Lock position for 30 seconds.
3. Slide the switch up to unlock the card.
4. Try to transfer files into the device.
What is the difference between Speed Class and Speed Ratings for SDTM/SDHCTM cards?
The speed rating measures maximum transfer speed for writing and reading images to and from the card, expressed as megabytes per second. However, video doesn't need as big a pipe because the video format is a smaller "fixed stream" that uses only a portion of the pipe. Unlike card write speeds that measure maximum performance, class ratings measure the minimum sustained speed required for recording an even rate of video onto the card. The class rating number corresponds to the transfer rate measured in megabytes per second. Class 2 cards are designed for a minimum sustained transfer rate of 2 megabytes per second (MB/s)1, while Class 10 cards are designed for a minimum sustained transfer rate of 10MB/s2. What does this difference mean for me?
Rated Speed (e.g. 15MB/s, 30MB/s, etc.) is maximum speed of the card and also what you would expect to approximately see in typical usage of writing or reading files on the card. This measurement is pertinent to still photography, especially for taking pictures with high resolution and/or saving in RAW format where the files created are very large. The faster the card, the faster it can save the file and be ready to take another picture. You really notice speed differences with high-megapixel DSLR and multi-shot burst mode. Still digital images shot on high-megapixel cameras should utilize fast data throughput (a large pipe), higher speed cards for improved performance. Higher speed cards can also improve how fast you can download (or upload) the files from the card to your computer. Speed Class is a minimum speed based on a worst case scenario test. The Speed Class is important for video mode or camcorders, where the device is actually saving a steady stream of data. The resolution and format of the video determines the amount of steady stream data. This translates to a minimum speed you need to guarantee that the video captured on the cards is recorded at an even, sustained rate with no dropped frames (which typically results in lost data and choppy playback). Compared to high-megapixel photography, video doesn't need as big a pipe because the video format is a smaller "fixed stream" that uses only a portion of the pipe. But you do need a minimum guaranteed speed for the SDHC card that satisfies the requirement of the data stream. Your camera's specifications should state the minimum SDHC Class Rating required. Using a card without the proper class rating on a more advanced camera, such as a high-definition (HD) camcorder or Digital Single Lens Reflex (DSLR) camera with HD video record settings is likely to result in an error message indicating that video can only be recorded at a lower definition setting.
What is MIL-STD-810G 516.6?
MIL-STD-810G 516.6 is a testing standard developed by the US Military and DoD to guarantee reliability in harsh environments. Our cards have been tested to withstand 1.5 tons force on impact and shock and over 15G vibration.
What is IPX8" or JIS 8 waterproof test?
These cards have been designed and tested to protect against water immersion for at least 30 minutes at a depth of 2.6 meter. By conducting this test to the IPX and JIS standards you can be sure that your cards data is secure to the highest standards
What is ISO 764 or DIN 8309 magnetic resistance?
This is tested by 3 expositions to a direct current magnetic field of 4,800 A/m where lose data or image on the card is unacceptable. These standards are routinely performed on high quality watches that need to survive the most challenging conditions that humans might experience. If you think you might need more magnetic protection than these test can check for, double check your health insurance before you find yourself in a risky situation.