The F1-X and F1-XRS models are based on BASF 6139 type disk drives. These are compatible with the BASF 6138 disk drives used in the previous 5,25" models, but have a slightly more compact design and a number of design flaws that affected durability were corrected.
The M1-X and M1-XRS models are based on NEC FD1035 type disk drives.
=== Variants ===