My T520 didn't come with a DVD security retention screw. How do I get one?
Many ThinkPads built prior to June 2009, had a security screw location (pictured below) which when installed, prevented the ultrabay from being ejected. This security screw benefited some users who were not switching out the DVD / CD RW drive for second HDD in an ultray bay tray, or ultrabay battery, and wanted to prevent the drive from being removed without tools.
Many ThinkPads shipped with the security screw included in the packaging in a separate bag, but not installed. The empty screw location prompted a number of questions from customers who thought that manufacturing had left out a screw. The screws can be ordered - the partnumber for T61 was FRU 42W3824 and FRU for the newer T400/500 and W500 systems 45N3853.
An assortment of frequently used case and chasis screws, including the security screws are available as FRU 42X4676.