Penetration resistance testing involves the insertion of a probe into a material with thickness. This can determine the change of state of a material that cures or sets, or the texture of a material (e.g. food, pharmaceutical preparations, or cosmetics) whose firmness is a measure of a quality. Cone probes are used for gels or viscous materials, needle probes for silicone pharmaceutical stoppers, and broader probes for penetrometers as used in cements and concretes.