wd10ezex-00zf5a0

WD Internal Drives Desktop & Mobile Drives
1

the 00RKKA0  access time is 20ms 

the 08RKKA0  access time is 15ms

the 00ZF5A0 access time is 20ms or 15MS ？？？

2

Somewhere around that dude

check the specs here

http://wdc.custhelp.com/app/answers/detail/search/1/a_id/1400#

you can use HD tune to test the drive performance