Durometer (Shore A) is a measurement of the hardness of an elastomeric compound. The numerical ratings for hardness run from lower numbered (less than 70) softer materials to higher numbered (greater than 70) harder materials, noting that fluorocarbon has a base rating of 75. This classification system is designed to work within a ±5 point range. All materials are not available in all hardnesses. Please refer to the Material Selection Guide, for the range of individual elastomers.