Those just push out from the inside. I buy them off eBay a dozen at a time but you may be able to just get a couple. I also put a couple of drops of super glue on them when seating. There is a small dot that aligns with a corresponding hole on the rim. Here's a set of four for $2.70 & free shipping: http://www.ebay.com/itm/4-pcs-New-OEM-Apple-Macbook-Pro-Unibody-Bottom-Case-Rubber-Feet-Foot-13-15-17-/301579648164?hash=item46378c3ca4