ISO 13921:2008 specifies the dimensions of 100° reduced countersunk head screws with internal offset cruciform ribbed or unribbed drive, with close or large tolerance normal shank and short or medium length MJ threads, in metallic material, coated or uncoated, with strength classes less than or equal to 1 100 MPa.

ISO 13921:2008 is applicable to the compilation of aerospace product standards.