I saw these on Amazon, in another post. It has the three bolt, which I think is sturdier than the Lithonia mounting arms, that don't have a through bolt. Also it says it's powder coated steel, and the shape looks like the American Electric arms. Although Amazon has another arm style for sale, it says it's for LED fixtures.

Designer's Edge Mounting Arm

Yes, they are better arms as they have a thru bolt which prevents sagging. The Lithonias will sag over time.

I recommend a better arm with a thru bolt than that one.

Unfortunately it seems these had been discontinued, which is shame. They look nicer than the other typical curved arms with no through bolting.

Choose an arm that have long enough section tangent to the pole, and tie around this section with 2 steel bands

With a mounting arm, the important fixing is the top one as that takes most of the weight and has the most force applied by pressure from the arm itself, so must be securely fastened with a large lag bolt or a through bolt, then as has been said a long length down the pole, at least as long as the arm.