This International Standard specifies the dimen­sions, surface and mechanical properties of normal­ and thin-walled tubing of designated metric sizes 3,4 mm to 0,3 mm, and of extra-thin-walled tubing of designated metric sizes 2,1 mm to 0,6 mm. Because no data are available. this International Standard does not specify stiffness properties for extra-thin-walled tubing of designated metric sizes 0,8 mm; 0,9 mm; 1,2 mm; 1,4 mm; 1,8 mm and 2,1 mm. This International Standard applies to rigid stainless steel needle tubing suitable for use in the manufac­ ture of hypodermic needles and other medical de­ vices primarily for human use. It does not apply to flexible stainless steel tubing because the mechanical properties differ from those specified for rigid tubing in this International Stan­ dard. However, manufacturers and purchasers of flexible tubing are encouraged to adopt the dimen­ sional specifications given in this International Standard. Standard.