You can look up more details about the model you have by using a
reference such as the MacTracker application, or online sites like
lowendmac.com.
A "MacBookPro9,2" is a 13" Mid 2012 model. Externally, they are
physically identical to the mid 2011 series.
If you are looking up Apple model details, you can usually spot if there
are external physical differences between two models by referring to the
"Model Number". All 13" MacBook Pros to date (apart from those with a
retina display) have a Model Number of A1278, so they have the same
physical body (but there will be internal component differences).
The skinit site's product descritions are confusing: it isn't clear what
the difference is between the product for the "Apple MacBook Pro 13",
the "Apple MacBook Pro 13 (2011) Laptop Bottom", and the "Apple MacBook
Pro 13 (2009/2010)", as after making the selection they all show a
laptop with the chosen picture on the top case, and all have the same
price. The "wrist guard" product appears to be different as it is
cheaper (but the picture is not helpful).
The "Laptop Bottom" one might be a separate product, but it isn't clear
which model the first one is for, when the 2009/2010 and 2011 options
cover all models prior to 2012, and there are no external physical
differences between any of those models, apart from the labelling on the
MiniDisplay/ThunderBolt port.
They don't appear to have product for the 13" MacBook Pro with retina
display (yet?).
If they can't describe their products clearly, nor answer questions
about the differences sensibly, perhaps they don't deserve your
business.
--
David Empson
dem...@actrix.gen.nz