The product brand for pleasure boat, models for M10 - M80. G1/8 - G2, head type for the cylinder head, trough type for Allen, the thread specifications for M8 - M80, nominal length is 8 ~ 20 mm, the thread tolerance is 6 g, black surface treatment for oxidation, material is carbon steel 22 h, product specifications for the M8 - M80, Allen process for cold heading.