For a dual laptop case the size would be the average size for a regular laptop case. In this case the max average would be about 18 inches. Of course there will be more specialized cases allowing for larger laptops.
Case logic makes different size cases, a 15 inch laptop will fit snugly in a 15 inch case.
A 13" laptop case.
It depends on the size of your laptop & how much organization you will need. You can get a genuine leather case for $60 and up.
I will recommend for you to go to Best Buy.com. They have amazing offers which is at unbelievable price ranging from $ 20 -30 and you have a lot of choices for which size fits your laptop.
The one that fits.
Laptop cases work on your screen size. from bottom left to top right it might be 15.6 that is the most common one.
The Mcklein hubbard leather laptop case comes in a maximum size of 16.5"x6.5"x12.5", however, it does note that it's back padded compartment does protect most laptops up to 17" in size.
Since a laptop is portable, one needs to have a durable and appropriate case. These come in many different styles, and not all are comparable. The size of the laptop should dictate the size. Also, if a person is going to be carrying books and other supplies, this should be factored into the purchase. Finally, the type of use is important. If the case is going to be in areas where it could be damaged easily, durability is key.
My Dell XPS 15 L502x fits nicely in the Pelican 1490 with foam (doesn't fit the CC liner). I just cut the foam so theres a pocket for cords underneath. If your 15inch laptop is smaller (probably is the XPS is huge) you can try the Pelican 1095CC. Follow the related link for their website.
the answer is yes and no because the king only fits the king size. the quenn mattress size only fits the queen size fits and the small well it only fits the small.
30 mm socket
It depends what you are talking about. External hard drives should have no problem running on a Vaio laptop but if you are going to try to replace the main HD, good luck. Make sure the size fits.