It's a Challenger Bread Pan. Sourdough needs to steam during its initial bake period and cooking in a cast iron pot allows for the dough to release its moisture which is turned to steam. After about 20 minutes the top is removed and the remaining bake takes place dry so it builds color.
Some bakers use a steam bath of some kind. Most use a cast iron or enamel Dutch oven. One popular pan is the Lodge combo cooker. It is like my Challenger but a fraction of the cost. It has a lid that can be reversed to use as the base and the pot part sits on top.
The Challenger is purpose made for baking loaves of bread so it is bigger and shaped differently. It also has some really neat handles on the lid that make it far easier to work with in a very hot one.
And yes, it makes a difference in the bake for sure.
It was super expensive but worth ever single penny IMO.
Right now its on sale and there is free shipping. I paid way more especially with shipping to Hawaii.