VEVOR Outdoor Stair Railing Kit, 4 FT Handrails 1-4 Steps, Adjustable Angle Black Aluminum Stair Hand Rail for The Elderly, Handrails for Outdoor Steps

I have handrails with 2 vertical posts and only one horizontal (ish) top rail and all 3 are aluminum. Even the welded bottom flange (with cover) is aluminum.

All the main part are aluminum.. I just installed and it’s very sturdy

The whole this is aluminum.

It is all aluminum.

I believe that all pieces are aluminum. It appears sturdy. We've had ours for two years and it still looks beautiful. I did use rust-proof black paint on the heads of the bolts and screws, just in case.

it's all iron I believe.

All 4 parts are aluminum

1/4 inch cement drill bit harden steel. Check the size of the bolts they send

The handrail will come with the correct bit and hardware.

you need to drill 5"1/13 holes in the concrete

I did not use the anchors that came with the handrail. I purchased concrete anchor screws. I think they hold much better. But I anchored to brick, so I was concerned about the supplied anchors not holding.

Vevor provides the bit with the kit.

Don’t know I installed mine on wooden steps.

3/8 bit is sufficient enough to anchor this.

No idea what that means. It's a base with four sides and takes two long screws.

We put it up last year and they still are strong and look like new. Ours are mounted in cement stairs.

The base has the seating plate with the holes to bolt to the surface where you have placed the railing…. The square cover drops down over the seating plate to “finish” the look of the railing and protect the bolts from weather…. Hopefully this helps

they are for fitting the 2 trim plats together. One side has holes and the other has tabs.

Not sure I had any holes in the base trim

You'll need to drill holes into the concrete steps to bolt the posts to. Four holes per post (bottom flange).

Location of drilling holes to install the expansion bolts to hold the railing in place. Comes with a cover cap. You need a cement drill bit

Not sure I understand the question. The holes in the base plate are where the bolts go to secure the handrail to the steps.