The prey item should be as big as the widest part of your snake. My baby bp is a couple months old and Is about a foot and a half long and I fed her two days ago I fed her a small adult mouse and it was big. I didn't think she was going to eat it but she did and eveything is fine. They will surprise you. But if you feed a prey item that is way to big it will break your snakes ribs which is obiously not good. How long is your snake? The way I do it is I grab the mouse by it's tail At the very end and I hold it in front of my bp and she will stoke and constrict it. Don't hold on to tight so when she grabs it comes right out of your grip.