Does this item come as a pair?

comes with two in the container. They fit either foot.

Would these be useful for Men size US 8?

My son uses one in his shoe..he wears 9 1/2.....I think a lot would depend on how much lift you need...I wear these daily, I do have another small cork wedge that I use under one of mine..my son changes them out with his dress shoes and boots....he didn’t like the way they fit in his tennis shoes....I’ve had mine for about 6 months and they have held up...I don’t foresee buying insoles any time soon......one other thing,some half insoles tend to slide down into the shoe, these don’t.they fit snugly in the heel...I’m extremely pleased with this insole....

Is this a pair or 1? Maybe a foolish question but I've been surprised before.

There are 2 in a package. You can use them for either foot as there is not right or left.

Are they confortable for longer period of time

I bought several Dr Foot lifts to put in several shoes. With different leg lengths, I've been told by a PT it's best to use all the time,so I do. It is comfortable.