I've noticed a lot of people complaining about rough country plastic spacers which in reality is not plastic but a fiberglass reinforced nylon which is really strong and can handle more pressure per square inch than most metals. Everyone thinks that since its metal its stronger when in reality could be a lot weaker. I have seen so many aluminum kits snap in half do to poor aluminum quality as well as it being a cast piece opposed to a forged piece. For those who don't know the differences a cast piece has molten aluminum poured into a mould to create the piece. A forged piece is a block of molten aluminum that has been compressed and let dry to a solid block then placed into a CNC machine and then the design is cut out. The problem with cast is that when its poured into an mould and let dry small air pockets are formed inside most not visible to the naked eye which create weak spots where the part can easily snap as I have seen happen to a lot of these cheap ebay kits. A forged piece is stronger as it reduces significantly the air pockets in the piece. If you weigh a cast and forged piece same design the forged piece will always weigh more as it has been compressed. Don't buy the cheap aluminum ebay kits, buy from a reputable company as they have done the research and testing. To those who still question the fiberglass reinforced nylon block strength I used to own an f150 with a 3" body lift with reinforced nylon blocks. The truck was in an accident on the highway and rolled over. The truck was totaled cab crushed in frame bent like crazy and twisted as well. The floor of cab ripped apart at spot welds. The blocks were intact, never bent, cracked or snapped a bolt. After seeing this I never question the strength of these reinforced nylon blocks as I know they will not fail. I have not heard of anyone saying these nylon blocks cracking or breaking, just negative remarks from those who don't know what they are talking about.