Ball Diameter Variation: The difference between the largest and the smallest single diameter measurements of one ball.

Ball Grade: A specific combination of dimensional, form and surface roughness tolerances. A ball grade is designated by the grade number.

Basic Diameter: The size ordered which is the basis to which the "Diameter Tolerance" specification applies.

Basic Diameter Tolerance: The maximum allowable deviation of any ball mean diameter from the Basic Diameter, in any shipment to fill orders for that Basic Diameter.

Container Marking Increment: The standard unit steps, in millionths of an inch, used to express the Specific Diameter.

Deviation from Speherical Form: The greatest radial distance in any radial plane between a sphere circumscribed around the ball surface and any point on the ball surface.

Hardness: The measure of resistance to penetration of the ball surface or truncated flat of the ball by a specified indenting shape as determined by specified methods.

Lot: A definite quantity of balls manufactured under conditions which are presumed uniform and which is considered and identified as an entirety.

Lot Diameter Variation: The difference between the mean diameter of the largest ball and that of the smallest ball in the lot.

Nominal Ball Diameter: The diameter value which is used for the purpose of general identification of a ball size, e.g. 1/4" 6mm, etc.

Passivation: A chemical treatment to remove corrodible surface impurities and to provide a protective film. This term is applicable to corrosion resisting balls only.

Specific Diameter: The diameter marked on the unit container, expressed in the grade's standard marking increment nearest to the mean diameter of the balls in that container.

Surface Roughness: Surface roughness consists of all those irregularities which form surface relief and which are conventionally defined within the area where deviations of form and waviness are eliminated.

Waviness: The more widely spaced circumferential component of surface texture. (Lacking standarized practices in this field, the specifications and tolerances for waviness are subject to agreement between manufacturer and customer.)