material:20#,16Mn,25w,ck45 cold drawn and stress-relieved (BK+S) honed inside : roughness 0.2um~0.8um; roller forming:<0.4um materialhardness(HB)thickness(mm)internal /out diameter(mm)20#/16Mn200-22010~25267.2/253.5,172/152.40,164.13/147.32 10~25250/299,250/280, 10~25220/273,220/255,10~25200/245,200/225,200/230,200/22010~25180/219,180/216,180/210,180/20310~16160/194,160/190,160/184,160/1805~15. ...