I have this railing and want to know if you can use it for stair rail in description it says horizontal railing is there some brackets i need to buy

Hello, and thank you for your interest in Trex! There will be a specific stair rail kit you can purchase that is meant to be used with a stair section. This kit is designed specifically for a horizontal section. If you need assistance ordering any components I would recommend reaching out to your local store. Thank you, Bradley, Trex Customer Care