I didn't know if my drive was 2.5" or 3.5" as I hadn't opened the case yet. I got a new computer, but on the old one I had some stuff that I didn't have time to translate. It costs less than $20 with shipping and arrived in 2 days. While many docking stations or enclosed hard drive enclosures were either 2.5" or 3.5", both would work. This does the same as the closed case but is not included. You can still use it as an external hard drive. This worked for my needs. And worth the money.