need help with hdd caddy for e6420 xfr model

I want to swap out the cd drive for a second hdd on my e6420 xfr

Seems ebay is full of generic caddys but which one do I need a few say they will fit the e6420 but do not include the xfr model, some have eject some do not ?

I would much rather buy it cheap if it's the same generic part but if it's not I need that info too