is the measure of the consistency of a grease, utilizing a penetrometer. Penetration is reported as the tenths of a millimeter (penetration number) that a standard cone, acting under the influence of gravity, will penetrate the grease sample under test conditions prescribed by test method ASTM-D-217. Standard test temperature is 25°C (77°F). The higher the penetration number, the softer the grease. Undisturbed penetration is the penetration of a grease sample as originally received in its container. Unworked penetration is the penetration of a grease sample that has received only minimal handling in transfer from its original container to the test apparatus. Worked penetration is the penetration of a sample immediately after it has been subjected to 60 double strokes in a standard grease worker; other penetration measurements may utilize more than 60 strokes. Block penetration is the penetration of block grease (grease sufficiently hard to hold its shape without a container).