Select Numero 10 LW Ball This LW(Lightweight) version of the Numero 10 ball reduces the weight of a size 5 soccer ball while still staying within the current standards set by the National Federation of State High School Association(NFHS). Weight: 14-14.5 ounces. Female Specific Injury Reduction: The alarming rate at which young women are experiencing very serious knee injuries in the sport of soccer is a greeat source of research and controversy. 2 year guarantee