Tiny spark plug porcelain fragments contain small, firm points that allow them to easily locate a point of fracture in glass. They can also be used to shatter car side windows. Due to their capacity to easily shatter glass, porcelain pieces from spark plugs are frequently referred to as “ninja rocks.”
Extremely durable aluminium oxide ceramic is used to construct spark plugs. The impact of the shard against the glass causes a minute structural defect, which rapidly spreads strain across the remainder of the screen, causing it to shatter. Although spark plug fragments are effective, they may not always work. Spark plug fragments may not shatter glass if they are not sufficiently sharp or if they are thrown with insufficient force. Spark plug porcelain fragments are also less effective on windshields due to the windshields’ enhanced resistance to impact due to a specific lamination characteristic.
In some states, spark plug fragments are considered weapons. Because they are occasionally used by thieves to break into vehicles. Carrying spark plug chips or fragments is considered a crime in California. Individuals found possessing spark plug chips face the possibility of a $1,000 fine or a six-month prison sentence.