Depends on how badly the plastic is scratched.
#10 Mirror Glaze is a polish for the heavier scrathes
#17 Mirror Glaze is a cleaner and will handle fine scratches
#18 Mirror Glaze is a detailer for keeping it pristine
They also have another product called PlastX Clear Plastic Cleaner & Polish. I don't have any experience with it, but their site says this about it:
Easy-to-use, rich gel formula quickly restores optical clarity to both rigid and flexible clear plastics. Removes light oxidation, chemical degradation, surface contamination, stains and light surface scratches with ease. Contains water-resistant polymers for lasting, durable protection to keep plastics clear and beautiful longer.