Don't buy one... I had a cervinis stalker bumper back in the day when they were fiberglass. One week after painting it, I hit the driveway and it cracked. It was more of a scrape than a hit. And not mention the extra work the painter had to do it in the first place
The urethane stalker from cervinis is the way to go. Better quality all around, less prep work, and a better more durable end product. I have had mine for 4 or 5 years no issues.