Normally it has a tube that you direct and its pressure is tremendous (at least in the beginning) .. As all sprays of this kind empty, the pressure decreases somewhat .. Logical!
It freezes after a certain point (like all) and needs a little time to "calm down" and then again..
I bought it for €2.90 and it's worth 1000 times more than one from a well-known chain with a computer that I paid €7 for and had no power at all!

For a PC, don't even think about it. It doesn't work at all. It doesn't have the tube needed to direct the air.

Very bad product. Initially, the air pressure is not strong enough and it only works for very superficial dust. Don't expect it to clean inside the keyboard, for example. Also, the more you press the valve to release air, the more the casing freezes and you can't hold it with your hand. But the worst part is that along with air, it often releases a liquid that smells like gas, probably from the pressure inside the container. In short, money wasted.

It does its job just fine. You don't need something more expensive for simple cleaning tasks like a computer