BP - slide bar change materials on static mesh

thanks you, i think i understand this tool now and purpose of it, but i cant connect it to + in BP. Last questions is about second slidebar with oppacity level with ''base" texture - i cant connect it together in one blueprint because its similar casts, i think i need to code funcionality of this slider in widget not in BP am i right? I found this slider to change alpha channel also in your topic.