HACKER KELLYS are available in square, hexagon and round fluted mill types. Hacker Forged Kellys are made from AISI 4142-H modified alloy steel to API specifications and normalized and tempered to 285/341 Brinell hardness. Available in 36' to 40' lengths in 31/2", 41/4" and 51/4" sizes. Mill Kellys are available in 3", 31/2", 41/4" and 51/4" sizes in lengths to 31'. Mill chemical and physical certifications furnished with each Kelly upon customer request. Connections furnished to meet customer requirements.