WD GLFS and HLFS
One of our clients had a WD Digital Velociraptor that was failing due to bad sectors. It was a 300GB WD Velociraptor GLFS type. The guys from warranty told us that they only have 300 GB Velociraptors HLFS type. The performance specs are the same, the only difference is that the HLFS has the SATA connectors on it’s heatsink, in order to allow the HDD to be placed in 3.5 inch bays, and use a standard 3.5 inch backplane.
But you can see the difference in the pictures below :
Western Digital GLFS
Western Digital HLFS