what are the clips made of?

They are made of either fiberglass or a very high-impact plastic. I doubt if you could damage it without trying hard, and you would probably use a metal tool to do so. I have purchased 4 pairs of these suspenders over the years (various colors) and have not broken a clip yet. The clip under the belt and hold well.

What is the length of these suspenders? I'm on the verge of needing a tall size and want to make sure this will work before buying.

My husband is a 3xl tall size and they are fine. Also the hook on the belt is a Godsend. He didn't want to wear the clip-ons any more because they snagged or dug into his back; these are definitely designed by a man or woman who had been through suspender problems and they are a genius idea!!! Good luck

how wide of a belt can you wear these with

Any width belt. The new Perry clips hold onto the belt better. I have been using these under the "Perry" name for over ten years and there are no spring clips to tear into your trousers.

On my navy blue dickies suspenders, i notice my adjustment tags are down very close to my belt and now midway on my chest,

Cold water and put them in the dryer. The elastic does stretch so if it happens shrink them like a shirt in the dryer. Works every time. You should wash the once or twice a week to prevent this and keep smelling good.