Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: How long do these last? Is there enough compressed air in one can? Is it "refillable"? I'm sorry if these questions sound weird, I'm new to this!
Document: This air is pretty good. It feels a little light after using it only briefly so I'm worried they don't last long but I've had them for a few weeks and still on my first can (I use it at least three times a week for computer cleaning). They also get cold REALLY quickly, so be careful holding it.
I'm only still on using one of these bad boys but let me tell you, they're exactly what you'd expect from compressed air.
I'm a DJ and an &#34;adult beverage&#34; got spilled on my very expensive MacBook Pro one evening. I poured the beverage out of the keyboard, then took the laptop home, let it dry out, and ordered this compressed air. When it came in I blew the machine out real well and saved myself three grand. No matter where you get this stuff it's expensive, might as well get it in bulk!
my new roomba rhett needs this to keep him running. the cans last one week. The roomba dust filter must be cleaned every time the roomba is run. Its easy to use, I do not understand the complaints.
They work well . . .its 4 for the price of 2 doesn't last very long. Great product tho .
Sturdy top and trigger. Will last a long time for what I use it for. Does what it is suppose to do. Would absolutely buy them again.
cheaper and fast delivery but I bought other brand of this kind and they're much better. These cans did not last long to me than the other brand.
Something was amiss, the design of the top mechanism, the pressure required for use, the rapidity in which the air was used up in each can. When you use a product for so long, when something is different, you notice it right away.The air pressure is as it should be, but it usually is, and doesn't warrant any extra stars because this is the way a can of compressed air should work. Try another brand.
Compressed gas (or air) are all the same. Order the one I mention or any other brand, but don't waste your money on this one. Compressed gas dusters (or whatever fancy name they're giving pressurized air these days) are all the same by any other name. So why order a product that wastes both your time and money? The price may be attractive, but in this case you are not even getting what you paid for.
as I had originally thought. Ordered the Compucessory Power Duster fromAmazon at a less expensive price than the Dust Off ones and I am very pleased with the product (The Compucessory) one, NOT the Dust-Off.I've deleted two stars because in thinking about it, NO can of compressed air should be difficult to use and these are; they are difficult to press to spray, and the top mechanism itself is not as it should be, just a simple press and spray.
Answer: They should last a long, long time since you really only use them to clean your keyboard and inside your computer (at least that's what I use them for).  You use them in short blasts to get the dust/particles out and keep your machinery running in good condition.  They are not refillable and I plan on this 4-pack lasting me well over a year, maybe even a year and a half.