VEVOR Wrought Iron Handrail, Fit 5 to 7 Steps Outdoor Stair Railing, Adjustable Front Porch Hand Rail, Black Transitional Hand railings for Concrete Steps or Wooden Stairs with Installation Kit

I did not receive the drill bit for the concrete anchors.  Not a big deal.  What is the correct size of bit for the holes?  I will just go get one. 

Could this be used for interior wood stairs? There are 4 steps next to a wall and 2 steps extend beyond the wall. thanks!