Magpul type 1 rail covers

[Heavy]

I just bought and "installed" these today. Im wondering what the longevity of them is. Mainly as far as does the heat effect them? I know it says heat resistant, but I'm courious as to whether there will be any material that sort of sticks to the hand rail after you've removed them. I've noticed that other brands of rail covers including Magpul type 2's are plastic instead of rubber. Is that because plastic is better? Any help or previous experience would be great. Thanks.