opinions on shock collar?

I have a 5 month old pupper he is the absolute sweetest but sometimes he doesnt listen and its so frustrating for me im trying so hard with training him. I have heard a little bit about shock collars and my MIL gave us one since it was too big for her pup. I havent used it just yet ive been holding off and i feel as if this is another way to steer him in the right direction. If yall have any opinions tips etc please drop a comment im literally desperate on trying to train my pup but i feel like its not getting anywhere.