and LB: chassis lubricants (suitability up to mild and severe duty respectively) GA, GB and GC: wheel-bearings (suitability up to mild, moderate and severe duty respectively) A given performance category may include greases of different consistencies. The measure of the consistency of grease is commonly expressed by its NLGI consistency number. The main elements of standard and NLGI's consistency classification are reproduced and described in standard “automotive lubricating greases” published by SAE International. Standard “lubricants, industrial oils and related products (class L) — classification — part 9: family X (greases)”, first released in 1987 by the International Organization for Standardization, establishes a detailed classification of greases used for the lubrication of equipment, components of machines, vehicles, etc. It assigns a single multi-part code to each grease based on its operational properties (including temperature range, effects of water, load, etc.) and its NLGI consistency number. Other types Silicone grease Silicone grease is based on a silicone oil, usually thickened with amorphous fumed silica. Fluoroether-based grease Fluoropolymers containing C-O-C (ether) with fluorine (F) bonded to the carbon. They are more flexible and often used in demanding environments due to their inertness. Fomblin by Solvay Solexis and Krytox by duPont are prominent examples. Laboratory grease Apiezon, silicone-based, and fluoroether-based greases are all used commonly in laboratories for lubricating stopcocks and ground glass joints. The grease helps to prevent joints from "freezing", as well as ensuring high vacuum systems are properly sealed. Apiezon or similar hydrocarbon based greases are the cheapest, and most suitable for high vacuum applications. However, they dissolve in many organic solvents. This quality makes clean-up with pentane or hexanes trivial, but also easily leads to contamination of reaction mixtures. Silicone-based greases are cheaper than fluoroether-based greases. They are relatively inert and generally do not affect reactions, though reaction mixtures often get contaminated (detected through NMR near δ 0). Silicone-based greases are not easily removed with solvent, but they are removed efficiently by soaking in a base bath. Fluoroether-based greases are inert to many substances including solvents, acids, bases, and oxidizers. They are, however, expensive, and are not easily cleaned away. Food-grade grease Food-grade greases are those greases that come in contact with food. Food-grade lubricant base oil are generally low sulfur petrochemical, less easily oxidized and emulsified. Another commonly used poly-α olefin base oil as well The United States Department of Agriculture (USDA) has three food-grade designations: H1, H2 and