Complex sentence: Wheel filters are designed to remove impurities in the process of injecting illicit drugs such as heroin, amphetamines or ecstasy or legal drugs such as benzodiazepines.
Split into simpler sentences: Wheel filters are designed to remove impurities in injectable drugs. They are often used to filter illegal injectable drugs such as heroin, amphetamines or ecstasy or legal drugs such as benzodiazepines.