under ur rides' hood/bonnet

factory/aftermarket insulation- whats it really for???

aftermarket: is this ok??

aftermarket i've seen:
-looks like roof insulating material (silver color on 1 side sandwiching white foam like backing) silver color side will face u when u open hood
-usually meausured to cover inside of hood and glued on using rugby (i have it on good authority that heat resistant double sided tape is recommended here instead)