These components are important in a few ways, the first being they prevent any oil drips from the distributor from falling on a hot turbo. Secondly they shield the distributor and its wiring from the intense heat given off from the turbo. Thirdly they hold a prominent place in the engine bay so it is important they look great!
A common corrosion point is the bolt holes on these heat shields causing them to rattle, and eventually fall off resulting in the oil feed pipe becoming loose.
These Abbott Racing reproductions are plated for anti corrosion.
Image is for illustrative purposes only