I have fitted Chrome Poles in 4 rooms. There are indeed different thicknesses of pole. The Metal ones at least. You need to judge the width, drop, and curtain material when choosing. A very wide window with a drop to the floor, or longer than a modern window height and heavy curtains will need a heavier guage pole. Also look at your fixing point. Is it a solid wall, stud wall, or do you mean to use something loke an already placed wooden curtain batton that was fixed when the house was finished. If so you need to make sure that your fittings will mount on the woioden batton. Also note that a wide window sometimes needs a pole that is joined in the middle. Can be a mare without a bit of consideation before you buy.