2nd dvd drive hard drive sata caddy?

Ok so basically i see dvd drives that replace the optical drive and allow you to put a 2nd hard drive on things like laptops.

The issue is i want one for a desktop as the ones i am finding are too small to fit in one of my desktops. Normally there is more than 1 expansion slot for an additional hard drive on MOST desktops but this isn't the case for mine as i am using a sff model and well the only way to add another hard drive is to take off my optical drive and swap it with some sort of expasion.

Anyone know where to buy one of these for a desktop optical drive as the ones for laptops are smaller

 

Thee are some on this page along with some 2.5" (for laptops) and some hard drives.

 

Like this?

 

This was actually what i was searching for, have you tried one of these personally?

The description says it includes a snap off dust cover but it doesn't show it at all in the pictures

Is there anything like this in metal or something for studier?