You're very welcome.
I believe the correct term is density, and you need to physically observe the illustration of the product.
HP notebooks will only work with the lowest density memory you can get (which is normally the most expensive).
Normally, the more individual black memory chips on each side of the board, the lower the density.
For example, I have posted a link to what the memory should look like. See the 8 black chips on the one side of the board?
This chip will also have 8 chips on the other side of the memory board, for a total of 16 little black chips.
http://www.newegg.com/Product/Product.aspx?Item=9SIA4UB1H73360
Now, this is an illustration of what you should NOT buy...it only has 4 chips on each side of the board.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820611577
It must cost more to manufacture the memory modules with 8 chips on each side than it does with 4.
Two other things...I noticed the service manual doesn't say anything...
The memory must also be non-ECC and Unbuffered.
Also make sure you get the same voltage memory as is currently installed in the notebook.
It will either be 1.5 (probably 1.5) or 1.35.
Don't mix them. You may have to check the sticker on the current chip and see if the voltage spec is listed.