My wife and I have BB 8100 series (she has an 8120 and I have an old Crimson). I inherited our 8100 Crimson because my wife dropped her 8120 out the window and I ran over it with my 4 wheel drive truck! Anyway, I gave her the better phone (yes, she is worth it) and in so doing wanted to add a memory card (which had been in the now crushed 8120) to the old Crimson 8100. So, if you go out there in forums you will find a mish mash of do's and don'ts about type, style, versions, etc. To clarify, I thought it might be nice to list what T-Mobile said was the safety range...all based on OS (see chart). Hope this helps someone out there trying to upgrade their Pearls!

BB OS Media Card Size Limit
4.2.0 Up to 2 GB
4.2.1 Up to 4 GB
4.2.2 Up to 4 GB
4.3.0 Up to 8 GB
4.5.0 Up to 8 GB
4.5.0.81+ Up to 16 GB
4.6.0+ Up to 32 GB

BlackBerry FAQ - BlackBerryFAQ is a great source of information for new users.

This particular thread - What type and size Media Card can I use in my device? - BlackBerryFAQ - has been up for several years.

Info in the FAQ as NJ stated. Thread closed.