Early 2011 MacBook Pro was running slow with its 2TB hard drive running at 5400rpm. The DVD drive was almost never used. The iFixit part allowed me to place the hard drive in the DVD bay and place an SSD drive where the hard drive originally sat. Now the computer fires up almost instantly and runs so much cooler as the 2TB hard drive is only accessed as needed. A stunning transformation for a 7 year old laptop.