Can someone let me what this code is doing.

Hi,
here is a piece code one of our developer wrote but there are no comments or anything and we have no idea what does this piece of code does. She is no longer with the company and we are not that much proficient in ASP.NET
this.pager.PageSize = Request["page_size"] == null ? 10 : int.Parse(Request["page_size"]);
what i am thinking is that it has something to do with the page size setting. the default i ...