This mechanism (as seen from the top of a complete bottom in Fig 3) is that which one ejects inserted side modules such as batteries, CD or DVDs.
The gears often strip, or other faults occur, when too much force is used to eject a stuck module.
You will get what is shown in the first two figures.
It takes some skill in disassembling the laptop to install these, so please be sure you consider your experience and capacity for this before you buy.
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