Алтыбұрышты болат. Стандарттар: МЕМСТ 2879-2006, МЕМСТ 8560-78. Өлшемдері: 3, 3,2, 3,5, 4, 4,5, 5, 5,5, 6, 6,5, 7, 8, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 20,5, 20,8, 21, 22, 22,5, 23,5, 24, 25, 25,5, 26, 27, 28, 28,5, 30, 31,5, 32, 33,5,