Brake seals

[Tofty]

Over the last few days i have been dismantling some of my numerous calipers and have noticed that on some of them the dust seal was missing.
I was wondering if they have a habit of falling out, werent fitted to some bikes, or are sometimes removed on porpose?
Any enlightening info would be most appreciated,
Cheers

[Garry]

i never use them - have found they tend to foul the pistons

i guess if you use the bike all year they might be worth retaining
but i only use mine in the summer