Can that hold in 1TB HDD? As is my MBP can only hold upto 500GB I heard.
If you have a Unibody MacBook Pro, your HDD bay can accept any HDD with a physical height of up to 12.5 mm, which means 1 TB HDDs will be accepted.
The Optibay adapter accepts HDDs with a maximum height of 9.5 mm, thus there can also be 1 TB HDDs be used in there, but you have to look closer at the specs.