Hardness:
The resistance to indentation. Measured by the relative resistance of the material to an indentor point of any one of a number of standard hardness testing instruments.

Hardness, Durometer:
An arbitrary numerical value which indicates the resistance to penetration of the indentor point into the rubber surface. Value may be taken immediately or after a very short specified time.

Hardness, Shore:
The relative hardness of an elastomer obtained by use of a Shore durometer instrument.

Height, Contact Line:
The axial distance from the outside seal face to the lip contact line.

Height, Helix Seal Rib:
The height of the helical ribs, measured perpendicular to the outside lip surface.

Height, Lip:
The axial distance from the outside seal face to the toe face.

Housing:
A rigid structure which supports and locates the seal assembly with respect to the shaft.

Hydroseal:
A sealing system having helically disposed elements formed on the shaft surface.