WD Red hard drives are designed and extensively tested for compatibility under 24×7 operating environment and for the demanding system requirements of home and small office NAS.
WD Red hard drives used to be available in 3.5″ but now Western Digital just announced the availability of WD Red in 2.5″ for the smaller form factor NAS. If you are using Synology NAS, you could also use the 2.5″ hard drives by buying the 2.5″ Disk Holder .
The new WD Red 2.5″ hard drives will comes in 2 versions for now, the 750GB which will be retailing for S$109 and the 1TB version which will be retailing for S$139.
Besides the new WD Red 2.5″ hard drives announcement, Western Digital also announced a new 4TB version for the WD Red 3.5″ hard drives and it will be retailing for S$329.
For comparison, the current prices (as of 7th September 2013) of WD Red 3.5″ hard drives that are listed by Fuwell  are 1TB: S$114, 2TB: S$165, 3TB: S$215.
WD Red – NAS Hard Drives