My book 2.5" 4TB

I bought a My book 2.5" 4TB external drive for PC. It has the size and heavy as My book 3.5" 5TB.
With P/N:WDBBGB0040HBK-NA Model:WDBBGB0040HBK-NESN
Did I get a wrong products? I have a 1TB 2.5" and 100GB 2.5", they are very small and light. Is there some mistake?
Please advice!

Not sure what your question is.

My Books are 3.5" drives.

Passports are 2.5" drives.

I am confused too. That is why I asked. Please look at bestbuy.ca page:
http://www.bestbuy.ca/en-ca/product/western-digital-wd-my-book-4tb-2-5-usb-3-0-external-hard-drive-wdbbgb0040hbk-nesn-wdbbgb0040hbk-nesn/10482142.aspx?path=766bda8c2a73eca809bb3b469822e0bcen02
or search model# WDBBGB0040HBK-NESN which I had mentioned before.
Hope you more clear what my question is?

Best Buy’s specifications page is wrong.