The pastry that sausage rolls are made from is puff pastry.
The puff pastry is made of fine layers and normally you have to be very delicate with it.
When using puff pastry for making sausage rolls the puff pastry needs to be slightly puffed, but not too much, so bashing it with a rolling pin reduces the amount it puffs up.
The Puff pastry which is also known as pâte feuilletée, is a flaky light pastry that is made from a laminated dough that is composed of bread dough and butter or some other solid fat.
The butter for the puff pastry is put inside the dough, making a paton which is repeatedly folded and rolled out before baking.
You can make your own puff pastry to make the sausage rolls from.