Types

• Before deciding how much memory you want to add to your BlackBerry Pearl 3G 9100, it's a good idea to familiarize yourself with the different types of SD cards that are available. Presently, all SD cards fall into three categories: SD, SDHC and extra-capacity SD (SDXC). Each category is comprised of standard-, mini- and micro-sized versions, except for the SDXC category, which only contains SDXC and microSDXC versions. SD, miniSD and microSD provide up to 2GB of memory, while SDHC, miniSDHC and microSDHC offer between 2GB and 32GB of memory. As a side note, SDXC and microSDXC cards offer between 32GB and 2TB of memory.
  
  

Physical Dimensions

• Another way to ensure that you're purchasing the right microSD card for the BlackBerry Pearl 3G 9100 is to become aware of the card sizes. MicroSD, microSDHC cards -- both of which are compatible with the Pearl -- and microSDXC cards are about the size of a fingernail, measuring 0.04 inches deep, 0.6 inches long and 0.4 inches wide and weighing 0.02 ounces. SD, SDHC and SDXC cards are about the size of a postage stamp and measure 0.08 inches deep, 1.3 inches long and 0.9 inches wide and weigh 0.07 ounces. MiniSD and miniSDHC cards are about a third the size of SD, SDHC and SDXC cards, measuring 0.06 inches deep, 0.8 inches long and 0.8 inches deep and weighing 0.03 ounces.
  
  

Speeds

• SD cards, in all their varieties, fit into two speed classes: Ultra-High Speed Class and Speed Class. These speed classes refer to a device's video-recording capability, which is offered by the BlackBerry Pearl 3G 9100. The SC is made up of four subclasses -- Classes 2, 4, 6 and 10 -- which work with normal and high-speed bus interfacing. Each speed class in the SC is compatible with the Pearl, but Classes 2, 4 and 6 are better suited to facilitate the type of video recording offered by the phone. Only SDHC and SDXC cards are compatible with UHSC interfacing, which is designed for large-scale, high-definition video.
  
  

Standards

• All SD technology-based cards, regardless of manufacturer, is produced in compliance with the standards established by the SD Association, an international technological-collaborative organization founded in 2000 by SanDisk, Toshiba and Panasonic. Currently, the SDA is comprised of more than 1,000 electronics-related companies. SD cards, in all formats, are used in more than 7,000 products worldwide.