The problem is...
The external case does not match the Apple's, but you can (technically) swap out the guts of the drives and put it in Apple Case. Of course that will void the warrantee and the internal guts fit the Apple case.
I've done it a few times and ran into a problem with 1 particular drive - it's IDE is on the opposite end of the board and would not fit the Apple case, so its Buyer Beware. If you can get the connector matching on the case, it should be a better buy.